The square shaft of our electric wrench is made of good steel material. Quickly replace and securely lock. Suitable for sockets, woodworking drill bits, bits, etc. Steel material, sturdy and durable. The edges are smoothly polished, fast and convenient to use, quick to replace, and firmly locked. Features - Color: Black. - Material: Alloy steel. - Size: 4.80X3.20X2.00cm/1.89X1.26X0.79in. - Note: There may be color differences among different batches. - High strength and hardness, high impact resistance, easy to use, durable. - Universally used for electric wrench head, easy to install and can be replaced at will. - Sturdy design, not easy to drop after installation. It is a friends and family who love DIY. - It is a good helper for family DIY, professional and durable. - Alloy steel material has high durability, resistance, electroplating treatment, flexible conversion, and only good materials can be durable. Package list: 1 x Expansion Bit Conversion Head