{"product_id":"m3-m6-black-304-stainless-steel-carriage-bolts-round-head-square-neck-coach-screws","title":"M3–M6 Black 304 Stainless Steel Carriage Bolts 8–100mm","description":"\u003ch2\u003eBlack 304 Stainless Steel Carriage Bolts — M3, M4, M5 \u0026amp; M6\u003c\/h2\u003e\n\u003cp\u003eUpgrade your fastening projects with these precision-crafted \u003cstrong\u003eblack 304 stainless steel carriage bolts\u003c\/strong\u003e. Featuring a classic round head and square neck design, these coach screws grip firmly into wood, metal, and composite materials — preventing rotation without the need for a wrench on the bolt head. Available in thread sizes M3, M4, M5, and M6 with lengths ranging from \u003cstrong\u003e8mm to 100mm\u003c\/strong\u003e, there's a size for virtually every application.\u003c\/p\u003e\n\n\u003ch3\u003eKey Features\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePremium 304 Stainless Steel\u003c\/strong\u003e — Excellent corrosion resistance for indoor and outdoor use\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eBlack Oxide Surface Finish\u003c\/strong\u003e — Sleek, modern look that blends seamlessly into dark timber, furniture, and metalwork\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRound Head, Square Neck\u003c\/strong\u003e — Anti-rotation design locks the bolt in place during tightening; no need to hold the head\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWide Size Range\u003c\/strong\u003e — M3, M4, M5, M6 diameters; lengths from 8mm up to 100mm to suit diverse projects\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVersatile Applications\u003c\/strong\u003e — Ideal for woodworking, furniture assembly, deck construction, DIY builds, and general fabrication\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSize Note:\u003c\/strong\u003e Dimensions are given as d × L (thread diameter × shank length, excluding head thickness). For example, M4 × 20 = 4 mm thread diameter × 20 mm length.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSpecifications\u003c\/h3\u003e\n\u003ctable\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMaterial\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e304 Stainless Steel\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSurface Finish\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eBlack\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eThread Sizes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eM3, M4, M5, M6\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eLength Range\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e8 mm – 100 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eHead Style\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eRound Head \/ Square Neck (Carriage Bolt)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eScrew Type\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMachine \/ Coach Screw\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eCountry of Origin\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eMade in Mainland China\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch3\u003eYou May Also Like\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/stainless-steel-self-tapping-screws-m2-2-m4-8-phillips-wood-hinge\"\u003e10PCS Stainless Steel Self-Tapping Screws M2.2–M4.8 Phillips\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/10pcs-durable-gold-blade-nut-metal-universal-trimmer-accessories-anti-loosening-line-left-hand-thread-replacement-parts-1\"\u003e10pcs Durable Gold Blade Nut Metal Universal Trimmer Accessories Anti-Loosening Line Left Hand Thread\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/12pcs-16mm-momentary-push-button-switch-1no-metal-2-pin-self-reset\"\u003e12pcs 16mm Momentary Push Button Switch 1NO Metal 2-Pin Self-Reset\u003c\/a\u003e\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003eLearn more: \u003ca href=\"https:\/\/www.osha.gov\/hand-power-tools\" target=\"_blank\" rel=\"noopener\"\u003eOSHA guidance on hand and power tools\u003c\/a\u003e\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions\u003c\/h3\u003e\n\u003ch4\u003eQ: What is the difference between a carriage bolt and a standard hex bolt?\u003c\/h4\u003e\n\u003cp\u003eA: A carriage bolt (also called a coach screw) features a smooth, domed round head and a square neck directly beneath it. When inserted through a pre-drilled hole, the square neck bites into the material and prevents the bolt from spinning as you tighten the nut — no wrench is required on the bolt side. Standard hex bolts have a hexagonal head that requires a wrench on both ends.\u003c\/p\u003e\n\u003ch4\u003eQ: Are these black 304 stainless steel carriage bolts suitable for outdoor use?\u003c\/h4\u003e\n\u003cp\u003eA: Yes. 304 stainless steel offers strong resistance to rust and corrosion, making these M3–M6 carriage bolts well-suited for outdoor applications such as deck building, garden furniture, and exterior woodworking. The black oxide surface finish also adds an extra layer of protection while maintaining a clean, modern appearance.\u003c\/p\u003e\n\u003ch4\u003eQ: How do I measure the correct length for my project?\u003c\/h4\u003e\n\u003cp\u003eA: The listed length (L) refers to the shank length only — it does not include the head thickness. For example, an M4 × 20 carriage bolt has a 4 mm thread diameter and a 20 mm shank length. To select the right size, measure the total material thickness you need to fasten and choose a bolt length that allows the nut and washer to be fully seated on the opposite side.\u003c\/p\u003e\n\u003ch4\u003eQ: Can these carriage bolts be used with wood and metal?\u003c\/h4\u003e\n\u003cp\u003eA: Absolutely. The square-neck carriage bolt design works excellently in wood, where the neck digs in to prevent rotation. For metal applications, a square hole or a close-tolerance round hole is recommended so the neck can grip securely. Always ensure the hole diameter matches the bolt's thread size for a proper fit.\u003c\/p\u003e\n\u003c!-- production-packaging-notice --\u003e\n\u003ch3\u003eProduction \u0026amp; Packaging Notice\u003c\/h3\u003e\n\u003cp\u003eTo maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.\u003c\/p\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"FAQPage\", \"mainEntity\": [{\"@type\": \"Question\", \"name\": \"What is the difference between a carriage bolt and a standard hex bolt?\", \"acceptedAnswer\": {\"@type\": \"Answer\", \"text\": \"A carriage bolt (also called a coach screw) features a smooth, domed round head and a square neck directly beneath it. When inserted through a pre-drilled hole, the square neck bites into the material and prevents the bolt from spinning as you tighten the nut — no wrench is required on the bolt side. 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Always ensure the hole diameter matches the bolt's thread size for a proper fit.\"}}]}\u003c\/script\u003e\n\u003cscript type=\"application\/ld+json\"\u003e{\"@context\": \"https:\/\/schema.org\", \"@type\": \"BreadcrumbList\", \"itemListElement\": [{\"@type\": \"ListItem\", \"position\": 1, \"name\": \"Home\", \"item\": \"https:\/\/68k0rh-yt.myshopify.com\/\"}, {\"@type\": \"ListItem\", \"position\": 2, \"name\": \"Home page\", \"item\": \"https:\/\/68k0rh-yt.myshopify.com\/collections\/frontpage\"}, {\"@type\": \"ListItem\", \"position\": 3, \"name\": \"M3–M6 Black 304 Stainless Steel Carriage Bolts 8–100mm\", \"item\": 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