4-Piece Impact Power Extension and Magnetic Bit Holder Set. Chrome vanadium steel construction. Spring loaded detent ball and chamfered ends to provide a secure fit into sockets. Set includes 1/4", 3/8", 1/2" Dr. Power socket extensions w. 1/4" hex shank. 1/4" Magnetic bit holder with 1/4" hex shank. Meets ANSI Standards.