6-40 x 5/16 Alloy Steel Socket Head Cap Screw gives engineers an internal-hex fastener for mechanical joints where socket engagement and dimensional consistency matter. The size callout supports bill-of-material consistency when socket-drive service locations cannot accept a substitute fastener. Applications often include tooling, fixture design, and processing equipment, especially where counterbored or close-clearance mounting is required. Internal hex drive access helps installation in compact assemblies, guards, housings, and fixture plates. This exact size supports industrial hardware, repair, and production requirements. Technical Highlights Material: Alloy Steel Thread: 6-40 Length: 5/16 in. Nominal Body Diameter: .138 in. Head Diameter: 0.218 in. min / 0.226 in. max Head Height: 0.134 in. min / 0.138 in. max Hex Key Size: 7/64 Drive Type: Internal hex socket Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.