M6 M8 Stainless Steel Expansion Bolts for Marble & Concrete — 304 / 201 SS, 20–40mm

Generally, select a bolt length that is at least 1.5× the thickness of the material being fastened, plus the depth of the anchor sleeve. For example, fastening a 10mm bracket into marble typically calls for a 20mm (≈3/4") or 25mm (≈1") bolt. When in doubt, go one size longer to ensure full sleeve expansion.

Load capacity depends on the base material, hole depth, and installation quality. In solid marble or concrete, M6 expansion bolts typically handle 200–400 lbs shear load and M8 bolts typically handle 350–600 lbs. Always consult a structural engineer for load-bearing applications, as actual values vary by installation conditions.

304 stainless steel variants offer good corrosion resistance for most outdoor and humid environments, including bathrooms, kitchens, and covered exterior applications. For coastal or highly corrosive settings, 316 SS is generally recommended. The 201 SS variants are best suited for dry or lightly humid indoor use.

These bolts use standard metric coarse threads (M6 and M8), following ISO 68-1 thread profiles. They are compatible with standard metric nuts, flat washers, lock washers, and threaded inserts available at any hardware store. No special adapters are required for most plumbing, electrical, and fixture mounting applications.

304 SS contains higher nickel content (typically 8–10.5%), giving it superior corrosion resistance and long-term durability — the right choice for outdoor, damp, or permanent installations. 201 SS is a cost-effective alternative with adequate tensile strength for dry indoor applications where corrosion exposure is minimal, such as interior wall anchoring in climate-controlled spaces.

The Triangle Pose variant (M8×40mm) features a triangular expansion sleeve geometry that distributes clamping force across three contact points rather than two. This generally provides more even grip in brittle materials like marble or ceramic tile, reducing the risk of cracking during installation. It is a good choice for thicker marble slabs or when anchoring into tile with a grout-free field area.

Yes, these expansion bolts are commonly used in ceramic tile, porcelain, and natural stone. Use a diamond-tipped drill bit to create a clean pilot hole, apply light pressure, and tighten gradually — never impact-drive the bolt. The Triangle Pose variant is particularly well-suited for tile applications due to its distributed clamping geometry.