Chrome Molybdenum Alloy Steel for exceptional strength and long lasting durability. High visibility laser etched markings with additional hard stamping on the opposite side. Surface drive technology. Pin hole available for use with pin and o-ring for secure socket retention. Packaged on a rail Set includes sizes: 5mm, 5.5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm and 15mm.