Abstract: A recess for fasteners such as screws, bolts and the like having, in axial alignment with the shank, a central recess of a conic-frustum shape which serves as a natural center for a driver tool or for a drill bit if it becomes necessary to drill out the fastener. The wrenching elements consist of a plurality of truncated conic segments having their common center line axis coincident with the central recess. The wrenching walls for loosening lying in a plane containing the center line axis of the fastener while the walls for tightening being sloped toward the tightening direction to provide for torque limiting.