5-Piece Metric 1/2-in drive deep, 6-point impact socket set includes 19, 20, 21, 22 and 23mm. This set is intended for use with an impact tool to provide maximum installation of heavy-duty fasteners. Constructed from chrome vanadium steel and heat treated for strength and durability with a black-oxide finish. Size callouts are laser etched. 6-Point sockets help prevent slippage and rounding off your fastener. Deep well is designed to reach a fastener on a bolt with exposed threads that a shallow socket cannot be used. Meets or exceeds ANSI specifications. Hassle-free lifetime guarantee