Armstrong Socket, Standard Length, Measurement System Imperial, 3/8 in Drive, Squared Drive, 12 Points Socket, 3/8 in Socket, 0.872 in Overall Length, 0.66 in Drive End Width, 0.563 in Socket End Width, 0.281 in Bolt Clearance Depth, 1/4 in Opening Depth, High Alloy Steel, Black Oxide