Stainless Steel 304 Grade Industrial Components: Material Properties and Selection Guide

Understanding Stainless Steel 304: Material Composition and Properties

Stainless steel 304 (also designated as AISI 304, EN 1.4301, or SUS 304) is the most widely used austenitic stainless steel in industrial applications worldwide. For Southeast Asian manufacturers considering sell on Alibaba.com opportunities in automotive components, industrial hardware, or consumer goods, understanding SS304's technical specifications is fundamental to meeting buyer expectations and competing effectively in global B2B markets.

Chemical Composition: The Foundation of Performance

According to AZoM's materials database, stainless steel 304 contains a balanced composition of chromium and nickel that delivers its signature properties ^[2]:

SS304 Chemical Composition (Weight %)

Element	Content Range	Function
Chromium (Cr)	17.5 - 19.5%	Forms protective oxide layer for corrosion resistance
Nickel (Ni)	8.0 - 10.5%	Stabilizes austenitic structure, improves ductility
Carbon (C)	≤ 0.08%	Controls hardness and weldability
Manganese (Mn)	≤ 2.0%	Enhances strength and workability
Silicon (Si)	≤ 1.0%	Improves oxidation resistance
Iron (Fe)	Balance	Base metal structure

Source: AZoM Grade 304 Stainless Steel Properties ^[2]

This 18-8 composition (18% chromium, 8% nickel) creates a stable austenitic microstructure that cannot be hardened by heat treatment but offers excellent formability and weldability—critical attributes for manufacturers producing brake cables, fasteners, tubing, and other automotive components.

Mechanical Properties: What Buyers Expect

Thyssenkrupp Materials' technical data sheet provides comprehensive mechanical property specifications that B2B buyers routinely reference when evaluating suppliers ^[5]:

SS304 Mechanical Properties (Annealed Condition)

Property	Value	Industry Significance
Tensile Strength	520 - 720 MPa	Determines load-bearing capacity for structural components
Proof Stress (0.2%)	≥ 230 MPa	Indicates yield point before permanent deformation
Elongation	≥ 45%	Measures ductility for forming and bending operations
Hardness (HRB)	≤ 92	Affects machinability and wear resistance
Density	8.00 g/cm³	Critical for weight-sensitive automotive applications
Melting Point	1450°C	Defines temperature limits for welding and heat treatment

Source: thyssenkrupp Stainless Steel 304 - 1.4301 Data Sheet ^[5]

These properties make SS304 particularly suitable for automotive brake system components, where moderate strength combined with excellent formability allows manufacturers to produce complex shapes while maintaining structural integrity under typical operating conditions.

Physical Properties at a Glance: Thermal expansion coefficient of 17.2 × 10⁻⁶/K, modulus of elasticity 193 GPa, and thermal conductivity 16.2 W/m·K define SS304's behavior under temperature variations—essential data for engineers designing components that experience thermal cycling ^[5].

Corrosion Resistance Performance: Where SS304 Excels and Where It Doesn't

Corrosion resistance is the primary reason buyers specify stainless steel 304 over carbon steel or lower-grade alternatives. However, understanding the limits of SS304's corrosion resistance is equally important for avoiding costly warranty claims and reputation damage on Alibaba.com's transparent marketplace.

Excellent Performance Environments

SS304 demonstrates outstanding resistance to:

Atmospheric corrosion in normal urban and rural environments
Organic chemicals including most food processing acids (citric, acetic, lactic)
Oxidizing acids such as nitric acid up to moderate concentrations
Alkaline solutions across wide pH ranges
Freshwater and steam conditions up to approximately 80°C

This makes SS304 the default choice for food processing equipment, kitchen fixtures, architectural trim, chemical containers, and indoor industrial components—applications representing substantial portions of the USD 135.81 billion global stainless steel market ^[1].

Limitations and Risk Environments

Reddit discussions among materials engineers and procurement professionals reveal critical limitations that Southeast Asian exporters must communicate transparently to buyers ^[4]:

316 is better for chlorides. If you're in a saltwater environment or dealing with chlorides, 304 will pit. Passivation is important for any stainless, and galvanic corrosion is a real risk when stainless contacts dissimilar metals ^[4].

SS304 is not recommended for:

Marine/saltwater environments (chloride-induced pitting corrosion)
Chemical processing with reducing acids (hydrochloric, sulfuric at elevated concentrations)
High-temperature applications above 870°C (sensitization risk)
Direct contact with carbon steel without isolation (galvanic corrosion)
Coastal architectural applications without regular maintenance

For these applications, buyers typically specify SS316 (with 2-3% molybdenum addition) or higher-alloy grades, accepting the 20-30% cost premium for enhanced performance ^[4].

Amazon Verified Buyer• Amazon.com

These worked just fine to cut down and use as spacers along #14 wood screws. They seem to indeed be stainless as I'm using them outside and they're not showing signs of rusting. They were straight and true to size, no complaints here ^[3].

5-star verified purchase, Tim A. outdoor use no rust feedback on SS304 tube

Amazon Verified Buyer• Amazon.com

The whole idea behind 304 stainless is that it's stainless and won't rust. This product was received with rust both on the inside and outside ^[3].

1-star verified purchase, Charles West rust issue complaint - indicates potential quality control or contamination issue

The contrasting Amazon reviews illustrate a critical point: while SS304 offers excellent corrosion resistance when properly manufactured and handled, quality variations exist. Surface contamination during fabrication, inadequate passivation, or mislabeled materials can result in premature corrosion—issues that trigger negative reviews and damage supplier reputations on B2B platforms.

Global Market Landscape: Size, Growth, and Regional Opportunities

Understanding the broader stainless steel market context helps Southeast Asian manufacturers position their SS304 products strategically when they sell on Alibaba.com. Market intelligence from Grand View Research provides authoritative data on market size, growth trajectories, and regional distribution patterns ^[1].

Market Scale: The global stainless steel market was valued at USD 135.81 billion in 2025 and is projected to reach USD 247.42 billion by 2033, expanding at a compound annual growth rate (CAGR) of 7.8% from 2026 to 2033 ^[1].

Grade Distribution: Where 304 Fits

The market is segmented by grade series, with austenitic stainless steels (300-series, including 304 and 316) dominating:

Stainless Steel Market by Grade Series

Grade Series	Market Share	Key Characteristics	Primary Applications
300-Series (Austenitic)	53%	Non-magnetic, excellent corrosion resistance, good formability	Food processing, chemical equipment, architecture, automotive trim
400-Series (Ferritic)	~25%	Magnetic, moderate corrosion resistance, lower cost	Automotive exhausts, appliances, cutlery
200-Series (Austenitic)	~15%	Lower nickel content, reduced corrosion resistance	Cost-sensitive applications, indoor fixtures
Duplex/Precipitation Hardening	~7%	High strength, specialized corrosion resistance	Oil & gas, marine, aerospace

Source: Grand View Research Stainless Steel Market Report ^[1]

SS304, as the most widely used 300-series grade, likely accounts for 30-35% of total stainless steel consumption—representing a USD 40-45 billion addressable market within the broader stainless steel industry.

Regional Market Dynamics

Geographic distribution reveals significant opportunities for Southeast Asian exporters:

Asia Pacific: Commands 69% of global stainless steel consumption, driven by China, India, Japan, and Southeast Asian manufacturing hubs ^[1]
North America: Steady demand from automotive, aerospace, and oil & gas sectors
Europe: Strong requirements for food-grade and architectural applications
Middle East & Africa: Fastest-growing regions, particularly UAE (100% YoY growth in automotive brake components), Ghana (127% YoY), and South Africa (150% YoY) ^[6]

For Southeast Asian manufacturers, the Asia Pacific dominance offers proximity advantages (lower shipping costs, faster delivery), while emerging markets in Africa and the Middle East present high-growth opportunities with less saturated competition compared to mature markets.

Application Segment Analysis

Building and construction represents the highest CAGR application segment, followed by automotive and industrial machinery. SS304's versatility positions it well across all these segments:

Automotive: Exhaust systems, trim, fasteners, brake components (cables, fittings)
Construction: Architectural trim, handrails, roofing, structural components
Industrial: Chemical processing equipment, food processing machinery, storage tanks
Consumer: Kitchen appliances, sinks, cookware, hardware

Future Market Intelligence: Yahoo Finance's stainless steel market forecast projects the market to start at USD 146.1 billion in 2026 and exceed USD 190 billion by 2031, with building construction accounting for 44.8% of total consumption and austenitic grades maintaining 53.2% share ^[7].

What B2B Buyers Are Really Saying: Real Market Feedback from Reddit and Amazon

Beyond technical specifications and market reports, understanding actual buyer sentiment and procurement criteria is essential for suppliers seeking to succeed on Alibaba.com. We analyzed discussions from Reddit's manufacturing, procurement, and engineering communities, along with Amazon verified purchase reviews, to capture authentic B2B buyer perspectives on stainless steel 304 components.

Material Selection Criteria: 304 vs 316 Debate

A highly-upvoted Reddit discussion in r/CNC (34 upvotes, 14 comments) reveals how buyers think about grade selection ^[4]:

Reddit User• r/CNC

304 for standard indoor use, 316 for saltwater/chemical environments. 316 is 20-30% more expensive, but 304 machines easier ^[4].

34 upvotes, 14 comments discussion on stainless steel grade selection for CNC machining

Reddit User• r/CNC

If you need it for sensor/EM applications, magnetic permeability is a huge spec. 316 is the way to go for those applications ^[4].

19 upvotes comment on specialized application requirements

These insights reveal that buyers make grade decisions based on three primary factors: environmental conditions (indoor vs. outdoor/marine), budget constraints (316's 20-30% premium), and specialized requirements (magnetic permeability for sensor applications). Suppliers who can articulate these trade-offs clearly in their Alibaba.com product listings demonstrate expertise that builds buyer confidence.

B2B Procurement Decision Factors

Reddit's procurement community discussions highlight what matters most to professional buyers:

Reddit User• r/procurement

A 5% cost reduction in procurement can equal a 20-30% sales increase in profit impact. But supplier diversification is critical, and ESG compliance is now a procurement responsibility ^[4].

32 comments discussion on procurement's strategic role in business

Reddit User• r/Business_China

Keep emails under 100 words. ISO certifications matter more than claims. Email the technical buyer first, not procurement ^[4].

40 upvotes comment from German purchasing manager on supplier communication preferences

These comments reveal critical insights for Southeast Asian exporters:

Price sensitivity exists, but total cost of ownership matters more: Buyers understand that cheaper suppliers may incur hidden costs through quality issues, delays, or compliance failures.
Certifications are non-negotiable: ISO 9001, material test reports (MTR), and third-party inspection certificates carry more weight than marketing claims.
Communication efficiency: Professional buyers appreciate concise, technical communication that respects their time.
ESG compliance: Environmental, social, and governance factors are increasingly part of procurement evaluation criteria.

Amazon Review Analysis: Quality Expectations and Pain Points

Analysis of 552 verified Amazon reviews for SS304 industrial tubing (ASIN B0BGPL81D6, 4.5-star rating) reveals specific quality attributes buyers value and common complaints ^[3]:

Amazon SS304 Product Review Sentiment Analysis

Rating	Percentage	Top Praise Points	Top Complaint Points
5-star	78%	True to size, no rust after outdoor use, good for projects, straight tubes	N/A
4-star	12%	Good value, acceptable quality	Minor surface scratches, packaging could be better
3-star	5%	Meets basic requirements	Dimensional variations (mm vs inch), inconsistent finish
2-star	3%	N/A	Surface contamination, delayed shipping
1-star	5%	N/A	Received with rust, significant size discrepancy, poor packaging

Source: Amazon.com SS304 Tube Reviews (552 reviews, 4.5 stars) ^[3]

Amazon Verified Buyer• Amazon.com

I have been looking for 1" od metal tubes to add weight pins to my Fitness Reality 810 XLC Super Max Weight Cage. These tubes should hold a static load of 250# easily ^[3].

5-star verified purchase, Jim V. fitness equipment application

The review data reveals that dimensional accuracy and surface quality are as important as material grade. Buyers expecting precise tolerances for mechanical applications become frustrated when products don't meet stated specifications. For B2B suppliers on Alibaba.com, this underscores the importance of:

Providing detailed dimensional drawings with tolerances
Specifying surface finish standards (e.g., 2B, BA, No. 4)
Including material test certificates with each shipment
Using protective packaging to prevent surface damage during transit

SS304 vs Alternative Configurations: Objective Comparison Table

This article uses stainless steel 304 as an entry point for discussion, but we emphasize that no single configuration is optimal for all scenarios. The following comparison table helps Southeast Asian manufacturers understand when SS304 is appropriate and when alternative configurations may better serve their target buyers.

Stainless Steel Grade Comparison for Industrial Components

Configuration	Cost Index	Corrosion Resistance	Machinability	Best For	Not Recommended For	Buyer Profile
SS304 (18-8)	100 (baseline)	Excellent for standard environments	Good - machines easily	Indoor industrial components, food processing, automotive trim, brake cables, fasteners	Marine/saltwater, chloride exposure, high-temperature >870°C	Cost-conscious buyers, standard applications, high-volume production
SS316 (16-10-2)	120-130	Superior - molybdenum addition resists chlorides	Fair - work hardens faster	Marine hardware, chemical processing, medical devices, coastal architecture	Budget-sensitive projects, non-corrosive indoor applications	Premium buyers, harsh environment applications, regulated industries
SS303 (Free-machining)	105-110	Good - slightly less than 304	Excellent - sulfur addition improves chip breaking	High-volume screw machine parts, complex machined components	Welding applications (hot cracking risk), high-corrosion environments	Manufacturers prioritizing production speed over maximum corrosion resistance
SS430 (Ferritic)	70-80	Moderate - magnetic, less corrosion resistant	Fair - lower ductility	Automotive exhausts, appliance trim, decorative applications	Structural components, forming operations, corrosive environments	Extreme cost-sensitive buyers, non-structural decorative applications
SS201 (Low-nickel)	60-70	Fair - reduced nickel content	Good	Indoor fixtures, cost-sensitive consumer goods	Outdoor applications, food contact, corrosive environments	Ultra-budget buyers, indoor-only applications, emerging markets
Duplex 2205	180-200	Exceptional - superior to 316	Poor - very hard, specialized tooling needed	Oil & gas, chemical tankers, high-stress corrosive applications	General purpose use, cost-sensitive projects, standard machining	Specialized industrial buyers, extreme environment applications

Cost Index: SS304 = 100 baseline; other grades shown as percentage premium/discount. Source: Industry pricing data and Reddit B2B discussions ^[4]

Key Takeaways from Comparison:

SS304 occupies the sweet spot for most general industrial applications, balancing performance and cost effectively.
SS316's 20-30% premium is justified only for chloride/saltwater exposure or specialized requirements (magnetic permeability, elevated temperature).
SS430 and SS201 offer cost savings but sacrifice corrosion resistance—suitable only for indoor, non-critical applications.
Duplex grades are specialized tools for extreme environments, not general replacements for 304/316.

For Southeast Asian exporters on Alibaba.com, the strategic implication is clear: offer multiple grade options and help buyers select appropriately based on their application environment. Suppliers who demonstrate this consultative approach build trust and command premium positioning.

Configuration Selection Guide: Recommendations for Different Supplier Types

Based on the market analysis, material properties, and buyer feedback presented above, we provide the following configuration selection guidelines for Southeast Asian manufacturers at different stages of their export journey on Alibaba.com.

For Small-Batch / Startup Suppliers

If you're new to sell on Alibaba.com or operating with limited inventory capital:

Start with SS304: It's the most universally recognized grade, reducing buyer education burden
Focus on standard sizes: Stock common dimensions (tubing OD 1/2" to 2", rod diameters 6mm to 50mm) rather than custom sizes
Emphasize certification: Obtain material test reports from your mill; this builds credibility more than price competition
Target emerging markets: Africa and Middle East buyers show highest growth rates (100-150% YoY) and may be more flexible on MOQs ^[6]
Avoid competing on price alone: Position on quality consistency, documentation, and communication responsiveness

For Medium-Volume / Growth-Stage Suppliers

If you have established production capacity and seek to expand market share:

Offer both SS304 and SS316: Capture both cost-sensitive and premium segments
Develop application-specific product lines: Create listings targeting automotive brake components, food processing equipment, or architectural hardware specifically
Invest in surface finish options: Offer 2B, BA, and No. 4 finishes to meet different buyer requirements
Pursue certifications: ISO 9001, industry-specific certifications (food-grade, marine-grade) differentiate from commodity suppliers
Leverage Alibaba.com tools: Use Verified Supplier status, product showcase features, and RFQ responses to increase visibility

For Large-Volume / Mature Suppliers

If you're an established manufacturer seeking premium positioning:

Full grade portfolio: Stock 304, 316, 303, 430, and duplex grades to serve all market segments
Value-added services: Offer cutting, polishing, fabrication, and kitting services
Technical documentation: Provide comprehensive material data sheets, CAD drawings, and application guides
Quality assurance programs: Implement third-party inspection, batch traceability, and warranty programs
Strategic partnerships: Consider Alibaba.com's Verified Supplier program and premium membership tiers for enhanced visibility

Market-Specific Configuration Recommendations

Target Market Configuration Strategy

Target Market	Recommended Grade	Key Requirements	Pricing Strategy	Communication Approach
North America (US, Canada)	SS304 standard, SS316 for marine	Material certs, dimensional accuracy, fast delivery	Premium pricing justified by quality	Technical documentation, concise emails under 100 words
Europe (Germany, UK, Italy)	SS304 with full traceability	ISO certifications, ESG compliance, REACH/RoHS	Mid-to-premium, transparency on costs	Formal communication, emphasize certifications over claims
Southeast Asia (regional)	SS304 cost-optimized	Competitive pricing, flexible MOQs, quick turnaround	Competitive pricing, volume discounts	Relationship-building, responsive communication
Middle East (UAE, Saudi)	SS304 for construction, SS316 for coastal	Fast shipping, Arabic documentation support	Mid-range pricing, project-based quotes	Relationship-focused, patience with decision cycles
Africa (South Africa, Ghana)	SS304 standard grade	Durability, after-sales support, flexible payment	Value pricing, emphasize total cost of ownership	Educational approach, build trust through transparency
South America (Brazil, Argentina)	SS304 for automotive, SS430 for decorative	Import documentation support, Portuguese/Spanish	Competitive pricing, currency flexibility	Warm relationship-building, regular follow-ups

Based on Alibaba.com market structure data and Reddit buyer preference discussions ^[4]^[6]

Why Alibaba.com: Platform Advantages for Stainless Steel Component Suppliers

For Southeast Asian manufacturers considering global expansion, Alibaba.com offers distinct advantages over traditional export channels and alternative B2B platforms. Understanding these advantages helps suppliers make informed decisions about their international sales strategy.

Global Buyer Network Access

Alibaba.com connects suppliers to millions of active B2B buyers across 190+ countries. For stainless steel component manufacturers, this means:

Diversified market exposure: Reduce dependence on any single geographic market
Year-round visibility: Unlike trade shows with limited duration, your products are visible 24/7
Targeted buyer matching: Alibaba.com's algorithms connect you with buyers actively searching for stainless steel components
Emerging market access: Reach high-growth markets (Africa, Middle East, Southeast Asia) that may be difficult to penetrate through traditional channels ^[6]

Data-Driven Decision Support

Alibaba.com provides suppliers with market intelligence tools that inform product development and pricing strategies:

Keyword trend analysis: Understand what buyers are searching for (e.g., "stainless steel 304," "corrosion resistant components," "SS304 specifications")
Competitive benchmarking: See how your products compare to similar listings in terms of pricing, specifications, and buyer engagement
RFQ market insights: Access real-time buying requests to understand current demand patterns
Performance analytics: Track which products, keywords, and markets generate the most inquiries and conversions

Success Story: AUTO JAW CO., LTD

Steven Chao, CEO of Taiwan-based AUTO JAW CO., LTD (automotive parts & accessories industry), exemplifies how suppliers can leverage Alibaba.com for growth ^[8]:

Joining Alibaba.com opened doors to buyers worldwide. With main customers in the USA, Japan, and Southeast Asia, AUTO JAW now receives an average of 35 inquiries per month, and their 2024 sales have grown by 176% compared to the previous year ^[8].

With a product catalog of 1,787 items and five years on the platform, Steven attributes success to continuously refining products, optimizing listings, and adapting sales strategies based on Alibaba.com's data insights. His experience demonstrates that sustained commitment to platform optimization yields measurable results.

Trade Assurance and Trust Building

For international B2B transactions, trust is paramount. Alibaba.com's Trade Assurance program provides:

Payment protection: Buyers' payments are held securely until they confirm satisfactory receipt of goods
Quality assurance: Clear specifications and inspection standards reduce disputes
Dispute resolution: Mediation support for any transaction issues
Verified Supplier status: Third-party verification of business licenses, production capacity, and quality systems builds buyer confidence

Comparison: Alibaba.com vs Traditional Export Channels

Export Channel Comparison for Stainless Steel Component Suppliers

Factor	Alibaba.com	Traditional Trade Shows	Direct Sales Team	Distributors/Agents
Initial Investment	Moderate (membership + marketing)	High (booth, travel, samples)	Very High (salaries, travel, offices)	Low (commission-based)
Market Reach	190+ countries, millions of buyers	Limited to show attendees	Limited by team size and budget	Limited to distributor networks
Time to First Inquiry	Days to weeks	Months (until next show)	Months (prospecting cycle)	Variable (depends on distributor)
Buyer Intent Visibility	High (search keywords, RFQs)	Medium (booth visitors)	Low (cold outreach)	Low (distributor controls relationship)
Control Over Pricing	Full control	Full control	Full control	Limited (distributor markup)
Customer Relationship Ownership	Direct relationship	Direct relationship	Direct relationship	Distributor owns relationship
Scalability	High (digital infrastructure)	Low (physical constraints)	Medium (hiring constraints)	Medium (distributor capacity)

Based on industry benchmarks and supplier experience reports

The table illustrates that Alibaba.com offers a balanced combination of reach, cost-efficiency, and control—particularly advantageous for small to medium-sized Southeast Asian manufacturers seeking global market access without the capital requirements of traditional export channels.

Action Plan: Next Steps for Southeast Asian Stainless Steel Suppliers

Based on the comprehensive analysis presented in this guide, we recommend the following action plan for Southeast Asian manufacturers seeking to succeed with stainless steel 304 components on Alibaba.com:

Phase 1: Product Preparation (Weeks 1-4)

Material certification: Obtain mill test certificates (MTC) for all SS304 stock, verifying chemical composition and mechanical properties
Dimensional documentation: Create detailed specification sheets with tolerances for each product SKU
Surface finish standards: Define and document surface finish options (2B, BA, No. 4, etc.) with sample photos
Photography: Invest in professional product photography showing dimensions, surface quality, and packaging
Packaging optimization: Design protective packaging that prevents surface damage during international shipping

Phase 2: Platform Setup (Weeks 5-8)

Complete company profile: Include production capacity, quality certifications, and export experience
Product listings: Create detailed listings with technical specifications, application examples, and downloadable documentation
Keyword optimization: Incorporate relevant keywords (stainless steel 304, SS304, industrial grade material, corrosion resistant components) naturally in titles and descriptions
Verified Supplier application: Begin the verification process to unlock enhanced visibility and buyer trust
RFQ response template: Prepare professional response templates for common buying requests

Phase 3: Market Testing (Weeks 9-16)

Launch with SS304 focus: Start with your strongest SS304 products to build initial traction
Monitor inquiry patterns: Track which products, keywords, and markets generate the most interest
A/B test pricing: Experiment with different price points to find optimal positioning
Gather buyer feedback: Request feedback from early customers to identify improvement opportunities
Iterate listings: Refine product descriptions, photos, and specifications based on inquiry quality and conversion rates

Phase 4: Expansion (Months 5-12)

Add SS316 options: Introduce premium grade products based on buyer demand signals
Develop application-specific lines: Create targeted product collections for automotive, food processing, construction segments
Expand certifications: Pursue industry-specific certifications based on target market requirements
Scale marketing investment: Increase P4P (Pay-for-Performance) advertising budget for top-performing products
Build customer relationships: Implement follow-up systems for repeat business and referrals

Critical Success Factors

Throughout all phases, maintain focus on these fundamentals:

Quality consistency: Every shipment must meet specifications; one bad batch can destroy reputation
Communication responsiveness: Reply to inquiries within 24 hours; professional buyers expect prompt responses
Documentation accuracy: Ensure all certificates, invoices, and packing lists are accurate and complete
Continuous learning: Stay updated on market trends, competitor activities, and Alibaba.com platform features
Patience and persistence: Building a successful export business takes time; expect 6-12 months before seeing consistent results

Market Opportunity Reminder: The global stainless steel market's projected growth to USD 247.42 billion by 2033, combined with Southeast Asia's strategic location and manufacturing capabilities, positions regional suppliers favorably for capturing market share through Alibaba.com's global marketplace ^[1].