Chrome molybdenum steel construction Wide lifting handles are easy to grip and support heavy loads SAE and Metric The GEARWRENCH 48-Piece 1/4 in. Drive Impact Socket Set, SAE/Metric are made from Chrome Molybdenum Ally Steel for exceptional strength and durability. The sockets utilize Surface Drive technology which provides off-corner loading for better grip and reduced fastener rounding. The Sockets are coated with manganese phosphate to resist corrosion. Secondary hard stamping Off-corner design reduces fastener rounding Manganese phosphate coating to resist corrosion Meets or exceeds ASME B107.2/B107.33M Blow mold case included Chrome molybdenum alloy steel (CR-MO) for exceptional strength and durability Set includes deep metric: 4, 4.5, 5, 5.5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 mm.