Features and Benefits: Designed to tackle the toughest jobs with solid durability and keeps them pounding job after job; Forged from the finest chrome-molybdenum alloy steel, the best choice for strength; Radius corner design extends the life of fasteners; design drives the side of the fastener instead of the corner; Has etchings for identification; This is an Impact Socket Adapter and it is 3/8 in. Female x 1/2 in. Male. It is a commonly size used for repairs. Finish is black oxide.