1/4"" Drive 6 Point Standard Socket, 5/16"", Radius corner design engages the flats of the fastener, not the corners, providing 15% - 20% more torque, Specifically heat treated for the correct balance of strength and durability, Manufactured to industrial specifications assuring a thin wall design with precise nut end dimensions, EYE-D laser etched markings optimize the size identification and SAE/Metric differentiation, SKU: ISN11953