Socket Cap Bolt Sets M3–M8 — A4 Marine 316 DIN 912

Why choose these A4 marine socket cap bolt sets

A complete bolted-joint kit in A4 marine grade 316 stainless steel — each set includes a DIN 912 socket cap (hex socket) bolt, a flat washer and your choice of nut (full hex, nylon lock or serrated flange). A4 is the right grade for boats, coastal installations and anywhere chloride or saltwater attack would rust standard A2. Allen-key drive gives high torque without rounding.

Sizes available

Bolt diameters M3, M4, M5, M6 and M8 paired with thirteen length options from 10mm up to 70mm — covering thin-section sheet joints right through to structural brackets. Each kit comes with a matching washer for the head side.

Pack options

Choose your nut style — standard full hex, nyloc (vibration-proof) or serrated flange (combined lock/washer) — in single sample, 2-pack or 5-pack quantities. Mix sizes and nut types across the basket to qualify for free UK delivery on orders over £20.

Typical uses

Boat hardware and deck fittings, trailer body work, outdoor sculpture and signage, machinery brackets, motorcycle and bicycle fixings, marine electrical boxes, watersports rigging, garden lighting and any threaded joint that needs to survive salt, weather or wash-down.

How to fit

Drop the bolt through the workpiece, fit the flat washer to the head side and run the chosen nut down the thread by hand. Tighten with an Allen key against an open spanner on the nut — nyloc and serrated flange nuts will resist vibration without needing additional lock washers. Avoid over-torquing small sizes; A4 stainless is softer than carbon steel.

Delivery

Same-day dispatch on orders placed before 2pm — free UK delivery on orders over £20.