METRIC, ¼” DRIVE, SURFACE DRIVE, STANDARD LENGTH, CHROME HAND SOCKETS.  Surface drive sockets are designed to retain contact with flat sides of nut to transmit high torque and reduce nut wear.Compared to FLAT DRIVE, SURFACE DRIVE utilizes contact on the larger area closer to the center of the bolt or nut.SURFACE DRIVE 1/4 Sq. Dr. Socket 7mm Surface Length 23mm