NSN 5306-01-389-0255

An externally threaded fastener whose threaded portion is of one nominal diameter, no. 10 (0.190 in.) (5 mm) or larger. It is designed with an internal socket or internal multiple spline for use with an internal driver. The head is beveled (conical) or cylindrical in shape. Items with cylindrical shaped heads must have an externally relieved body. A locking feature may be incorporated in the design of the head or threads. See also screw, cap, socket head. Excludes setscrew; screw, shoulder; bolt, shoulder; screw, externally relieved body; bolt, externally relieved body; and screw, machine.