Abstract: A plurality of circumferentially-spaced driving lugs are formed on the improved square-drive tang of a wrench, such as a ratchet wrench; and these driving lugs cooperate with a corresponding plurality of recesses or pockets formed in the top portion of an improved interchangeable square-drive socket, thereby providing for improved torque transmission which is supplemental to, and not a substitute for, the square drive. The improved wrench is compatible with conventional sockets, and the improved socket is compatible with conventional wrenches.