Ko-ken Tools 3/8 Sq. Dr. Universal NUT GRIP® Socket - 13mmNut Grip, 3 8" drive, Standard Length, Chrome Hand Sockets. NUT GRIP is Ko ken's special design for non magnetic nuts bolts to be held firmly in a 6 point socket. The design consists of two balls held in place by a spring steel ring. Our nut grip sockets are unique to Ko ken and truly a revolutionary way of approaching this type of socket. Our fastener holds nuts and bolts in place without the use of magnets. Our system is built with a coil spring and