Armstrong Drive Socket, Deep Length, Measurement System Metric, 1/2 in Drive, Square Drive, 12 Point Socket, 12 mm Socket, 3.205 in Overall Length, 0.858 in Drive End Width, 0.728 in Socket End Width, 0.406 in Bolt Clearance Depth, 0.539 in Opening Depth, Ball Locking, High Alloy Steel, Chrome Plated