The screwdriver has no round head, because the round head has no torque at all. One word is to ensure torque, and the cross can make the power distribution more evenly. Press the power source to divide the manual screwdriver and the electric screwdriver; Press bit or cutter head to divide the character (flat head) and Cross (phillips).

The cutter head of the high-quality screwdriver is made of spring steels with relatively high hardness. A good screwdriver should be hard but not crisp and tough. When the opening of the screw head becomes bald and slippery, you can use a hammer to tap the screwdriver to remove the slot of the screw deeper, which is convenient to unscrew the screw. The screwdriver should be unscathed; screwdriver is often used to pry things, which requires certain toughness without bending or folding. In general, I hope the hardness of the screwdriver head is greater than HRC60, rust-resistant.