Flat Socket Cap Screw - 4-40 x 3/8" - Steel Alloy - Thermal Black Oxide - FT - UNC - 100 Pk

Cap screws are designed to go through a hole or nut that is pre-tapped to form a mating thread for that screw. flat head screws are used when protrusion of the fastener above the mating surface is unacceptable. allen/hex keys are used to drive the screw.