Stanley Proto J4708SPL 1/4-Inch Drive Spline Socket No.8, 1/4-Inch Proto Spline tools are designed to service high tensile strength fasteners used widely on military and commercial aircraft Spline sockets help tighten high strength bolts to high torque loads Spline sockets on spline fasteners help deliver twice the torque of 12 Point wrenches on double box fasteners Spline helps reduce foreign object debris (FOD) by having a precise fit between the fastening tool and its fastener