Made from selected alloy steel with approximately a 140 operating range Chrome vanadium steel manufactured 1/4" High quality this product is made from High-quality chrome vanadium steel CRV. Durable Quenching heat treatment to the whole makes the hardness high, the product is durable. Beautiful The surface of the product has been chrome plated so that it is rust proof and beautiful. Easy to use The product is suitable for all the hexagonal side handle four square hole groove, the sleeve can be conversed to each other freely, easy to use.