3-56 x 7/8 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. The size callout supports replacement sourcing without changing the specified size when machine frames and brackets cannot accept a substitute fastener. Common uses include engineering departments, tooling, and manufacturing plants, where internal hex installation helps keep the joint accessible. Verified head dimensions and hex key size help engineering departments check fit before ordering. This keeps the listing focused on the fastener geometry rather than broad catalog language. Technical Highlights Material: Alloy Steel Thread: 3-56 Length: 7/8 in. Nominal Body Diameter: .099 in. Head Diameter: 0.154 in. min / 0.161 in. max Head Height: 0.095 in. min / 0.099 in. max Hex Key Size: 5/64 Drive Type: Internal hex socket Call 773-775-7900 or email Sales@coldheaders.com for pricing, availability, or a quote.