Bolts

Stainless steel bolts in A2 (304) and A4 (316): part threaded hex head bolts from M5 to M48, cup square (carriage) bolts, eye bolts, U-bolts, hanger bolts and hammer head bolts, plus throughbolts and drop-in anchors for concrete and weld studs.

Hex head bolts are made to ISO 4014 and DIN 931, and many A4 sizes come in both property class A4-70 and the stronger A4-80. Imperial hex bolts come in UNC, UNF and BSW threads. Cup square bolts are made to DIN 603 in A2 and A4 from M5 to M16. Fully threaded hex set screws have their own Hexagon Set Screws collection.

Choose A2 for indoor and inland outdoor use; choose A4 near the coast or wherever salt is present.

Frequently asked questions

What bolts does Simfix stock in A2 and A4 stainless steel?

Part threaded hex head bolts (ISO 4014 and DIN 931) from M5 to M48, cup square bolts (DIN 603) from M5 to M16, eye bolts, U-bolts, hanger bolts, hammer head bolts, throughbolts, drop-in anchors and weld studs. Hex head bolts, cup square bolts and eye bolts come in both A2 (304) and A4 (316); the throughbolts and drop-in anchors are A4 only.

What is the difference between a hex head bolt and a hex set screw?

A hex head bolt (ISO 4014 or DIN 931) has a plain, unthreaded section of shank under the head and threads only along the lower part. A hex set screw (ISO 4017 or DIN 933) is threaded along its full length. Use a part threaded bolt where the plain shank sits in the shear plane; use a set screw for blind holes or thin material.

What is a cup square bolt used for?

A cup square bolt, also called a coach bolt or carriage bolt, has a domed head and a square shoulder under it that bites into the wood and stops the bolt spinning while you tighten the nut. Simfix stocks them to DIN 603 in A2 (304) and A4 (316), M5 to M16, for decking, fencing, gates and other timber joints.

Are Simfix eye bolts rated for lifting?

Only use an eye bolt for lifting when the specific product has a documented working load limit and instructions for the intended lift. A shape, standard number or CE label alone does not establish the rating for your application. Check load direction, installation and the manufacturer’s instructions before use.

Should I choose A2 or A4 stainless steel bolts?

Choose A2 (304) for indoor use and general outdoor and inland work. Choose A4 (316) near the sea, around swimming pools or anywhere exposed to salt or chlorides. The difference is molybdenum: A4 contains 2% to 3% molybdenum, which resists the chloride pitting that A2 does not.

Sizes, grades and pack quantities vary by product type. Check the individual product listing for the exact specification and current availability.