A socket screw driven with a socket wrench, allen key, allen wrench. Socket cap screws are similar to machine screws and are often fully threaded but may be partially threaded when indicated The term socket head cap screw typically refers to a type of threaded fastener whose head diameter is nominally 1.5 times or more that of the screw shank (major) diameter. 18-8 Stainless Steel offer the Fastener Industry standard for corrosion and rust resistance Recommended for use in exterior applications, or those that are exposed to fresh water moisture Socket Cap Screws 18-8 Stainless Steel - 5/16-18 x 3/4 (FT) Qty-25