Special Features:

Screw, cap, socket head, self locking (requested name)

Properties:

An externally threaded fastener whose threaded portion is of one nominal diameter. The head has an internal socket or multiple spline for use with an inserted driver. A locking feature may be incorporated in the design of the head or threads. Excludes items with bevel (conical) heads. See bolt, internal wrenching. Excludes screw, shoulder; and screw, machine.