5/8-18 x 5/8 Alloy Steel Socket Head Cap Screw supports industrial fastening where the socket head, internal hex drive, and verified head dimensions help match existing designs. The size callout supports replacement sourcing without changing the specified size when repair inventories cannot accept a substitute fastener. It is frequently used in industrial automation, production lines, and fixture design when socket engagement is preferred over external-wrench access. Alloy steel supports strength-focused fastening where clamp load and repeatable assembly are important. This keeps the listing focused on the fastener geometry rather than broad catalog language. Technical Highlights Material: Alloy Steel Thread: 5/8-18 Length: 5/8 in. Nominal Body Diameter: .625 in. Head Diameter: 0.921 in. min / 0.938 in. max Head Height: 0.616 in. min / 0.625 in. max Hex Key Size: 1/2 Drive Type: Internal hex socket Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.