M6–M12 Countersunk Hex Socket Expansion Bolts — 304 & 201 Stainless Steel, A-Type & B-Type

A general rule: add your fixture thickness to the required embedment depth in the base material. For concrete or masonry, embedment is typically 25–40mm beyond the fixture face. For example, a 10mm-thick bracket anchored into concrete with 30mm embedment needs at least a 40mm (≈1-9/16") bolt. When in doubt, size up — a longer bolt with proper embedment is generally safer than a shorter one. Available lengths run from 40mm (≈1-9/16") to 150mm (≈5-7/8").

Load capacity depends on bolt diameter, embedment depth, base material strength, and installation quality. Generally, M6 bolts handle lighter fixture loads (shelving, conduit straps), while M10–M12 bolts are suited for heavier structural applications (handrails, equipment frames). For safety-critical or load-bearing installations, always consult a licensed structural engineer and refer to the bolt manufacturer's published load tables.

304 stainless steel variants are generally suitable for outdoor, humid, and mildly corrosive environments — a common choice for exterior concrete anchoring. 201 stainless steel provides moderate corrosion resistance and is better suited for indoor or sheltered outdoor use. Neither grade is typically recommended for marine or highly chloride-rich environments; 316 SS would be the appropriate choice in those conditions.

These bolts use standard ISO metric coarse threads (M6, M8, M10, M12), compatible with standard metric nuts, threaded inserts, and tapped holes. The internal hex socket accepts a standard Allen/hex key — typically 4–5mm for M6, 6mm for M8, 8mm for M10, and 10mm for M12, though we recommend confirming the exact key size for your specific variant.

A-Type features a flat countersunk head with a standard countersink angle, designed to sit flush with the surface when fully driven into a matching countersunk hole. B-Type has an alternate countersink geometry suited for fixtures or substrates with a different pre-drilled countersink angle. Check your fixture's countersink specification — using the wrong type can result in the head sitting proud of the surface or rocking in the hole.

Choose 304 stainless steel for outdoor installations, areas exposed to moisture or humidity, food-adjacent environments, or anywhere long-term corrosion resistance is a priority. Choose 201 stainless steel for dry indoor applications where cost efficiency matters and exposure to moisture is minimal. Both grades are structurally capable for typical anchoring tasks; the difference is primarily in corrosion performance over time.

Pack quantity is selectable at checkout. Depending on the size and type chosen, options include 1, 2, 5, 10, or 25 pieces. Multi-piece packs offer a lower per-unit cost and are ideal for larger projects or keeping spares on hand. Note that not every quantity option is available for every size/type/material combination — select your Size first to see available Amount options.