Armstrong Drive Socket, Deep Length, Measurement System Metric, 3/8 in Drive, Square Drive, 12 Point Socket, 18 mm Socket, 2-1/2 in Overall Length, 0.949 in Drive End Width, 0.949 in Socket End Width, 0.661 in Bolt Clearance Depth, 1.378 in Opening Depth, Ball Locking, High Alloy Steel, Full Polished Chrome Plated