5/16-18 x 4 Alloy Steel Socket Head Cap Screw is specified when a machine assembly needs a high-strength alloy steel socket screw with predictable head and drive geometry. This size keeps the specified 5/16-18 thread and 4 in. length visible for matching drawings and maintenance records. The screw is useful across engineering departments, assembly equipment, and fixture design when a compact internal-hex fastener is required. The socket head form provides a cylindrical head suited to counterbores and recessed mounting pockets. The combination of product name, size, material, and verified head data improves search clarity for engineers and buyers. Technical Highlights Material: Alloy Steel Thread: 5/16-18 Length: 4 in. Nominal Body Diameter: .312 in. Head Diameter: 0.457 in. min / 0.469 in. max Head Height: 0.306 in. min / 0.312 in. max Hex Key Size: 1/4 Drive Type: Internal hex socket Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.