Screw UNF 0-80x12 Countersunk T5

Countersunk Head Screw - T5 Drive 

Flat head or countersunk is a Conical, with flat outer face and tapering inner face allowing it to sink into the material. a Torx is a star-shaped "hex lobular" drive with six rounded points. It was designed to permit increased torque transfer from the driver to the bit compared to other drive systems.