NSN 5305-01-255-2638

An externally threaded fastener designed for insertion into holes in assembled parts, for mating with a preformed internal thread and for tightening or releasing by torquing the head. the threaded and unthreaded portions are both of the same nominal diameter of 0.190 inch (5 mm) or larger. head dimensions and sizes of threaded and unthreaded portions shall conform to internationally recognized fastener standards. the thread length being the controlled dimension, the grip length is not specified. a locking feature may be incorporated in the design of the head or threads. the head is not designed to be held or driven with an inserted driver or by the thumb and fingers. excludes bolt,machine; bolt,externally relieved body; bolt,internal wrenching; and screw,cap,socket head.