The BB84 Half Surface 4-1/2” Door Hinge is a specialty hinge. The hinge leaf will mount on the door frame in the standard mortise position and the other leaf mounts on the door face. These are five knuckle, two bearing with square edges. They are constructed of 10 gauge (.134”) steel that is then plated to the desired finish. We ship in boxes of 3 hinges with the wood and machine screw.