The deepened drive end of the KO-KEN Sleeve-Drive tools prevents the sometimes "wobbly" connection between pulse tool - extension - socket. An O-ring inside Sleeve-Drive optimizes the perfect fit of extension bars and sockets on the anvil to the effect, that the exactness of the required torque given by the pulse tool 1/2 Sq. Dr. Extension Socket 15mm 6 point 150mm Sleeve Drive