Armstrong Drive Socket, Deep Length, Measurement System Imperial, 1/2 in Drive, Square Drive, 12 Point Socket, 1/2 in Socket, 3.185 in Overall Length, 0.86 in Drive End Width, 0.745 in Socket End Width, 0.48 in Bolt Clearance Depth, 0.65 in Opening Depth, High Alloy Steel, Black Oxide