Screwdrivers do not have a round head, because the round head has no torque at all. One word is to ensure that there is torque, and the cross can distribute the force more evenly. According to the power source, there are manual screwdrivers and electric screwdrivers; According to the head or knife head, there are flat heads and phillips.

The bits of high-quality screwdrivers are made of spring steel with relatively high hardness. A good screwdriver should be hard but not brittle, hard and tough. When the opening of the screw head becomes bald and slippery, you can use a hammer to hit the screwdriver, and the groove of the screw is deeper, so that the screw can be unscrewed, and the screwdriver should be unscathed; Screwdrivers are often used to pry things, which requires a certain toughness without bending or bending. In general, it is hoped that the hardness of the screwdriver head is greater than that of HRC60 and it is not easy to rust.