Fed. Spec: ANSI B107.2 Features • SUPERTORQUE® lobular openings for greater turning power without deforming the fastener. • 13/16" square opening threads stud into wheel. • 1-1/2" hex opening engages and tightens the wheel lug nut. • Suitable for use with pneumatic and electric impact wrenches. • Specially heat treated for impact use to provide long life, safety, and durability.