5/8-18 x 4 1/4 Alloy Steel Socket Head Cap Screw provides a strength-focused alloy steel socket cap screw option for mechanical assemblies requiring this exact size. The exact 5/8-18 x 4 1/4 size helps buyers align the fastener with service work where the exact thread and length are already defined. Common uses include tooling, assembly equipment, and maintenance repair, where internal hex installation helps keep the joint accessible. Internal hex drive access helps installation in compact assemblies, guards, housings, and fixture plates. Those verified dimensions support counterbore checks, tool selection, and replacement fastener review. Technical Highlights Material: Alloy Steel Thread: 5/8-18 Length: 4 1/4 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.