The square shaft of our electric wrench is made of steel. Quickly replace and securely lock. Suitable for sleeves, woodworking drill bits, drill bits, etc. Steel material, sturdy and durable. The edges are smoothly polished, to use, quick to replace, and tightly locked. Features - Color: Silver. - Material: Chromium Vanadium Alloy Steel. - Size: 5.00X4.00X2.00cm/1.97X1.57X0.79in -Note:There is some color difference between the different product batch. - High strength and hardness, high impact resistance, easy to use and durable. - The universal electric wrench head is easy to install and can be replaced at will. - Rugged design, not easy to fall after installation. It is a present for friends and family who like DIY. - and good craftsmanship ensure its durability and practicality. - 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