Imperial Socket Set Cup point, ASME B18.3

A socket set screw with cup point and a hexagon drive, also known as a grub screw.  In stainless steel A2 (304) to ASME B18.3 with unified coarse (UNC) thread.  A hex key, sometimes referred to as an allen wrench or allen key, or a hex driver is required to tighten or loosen a socket screw. Designed without a protruding head they can be driven fully into pre drilled holes. Socket set screws are generally used to secure a object within or against another object, the most common example would be to secure a pulley or gear to a shaft.  Also commonly found on door handles, bikes and mobile phones.