Flat Head, Socket Drive, Stainless Steel Flat head is cone shaped for use in countersunk holes and has a flat top that fits flush with the mated surface Internal hex drive has a hexagonal slot that turns using an Allen key driver 18-8 Stainless steel provides corrosion resistance Drive Size 3/32" Hex The stainless steel socket cap screw has a plain finish and a flat head with an internal hex drive. Stainless steel resists corrosion and may be magnetic. The flat head is cone shaped for use in countersunk holes and has a flat top that fits flush with the mated surface. The internal hex drive, also known as a hex-socket drive, has a hexagonal slot that requires an Allen key driver, also known as a hex key or Allen wrench. Socket cap screws are threaded fasteners that have a cap head with an internal socket drive for installing in areas with limited side clearance. These screws are available with a variety of head shapes, which determine how the screw interacts with the mating surface, and drive styles, which determine the type of tool required to install the screw.