M35-CO High Speed Steel Versatility Our step drill is a combination of HSS-CO (M35) and industrial titanium coating to make them more durable. Easy continuous drilling on HRC40 steel plate without hardness. The two-groove spiral design also makes it easier to remove debris for more efficient drilling operations. There is a sense of pause at each step, so it can fit any size you want. The universal 3/8 triangular shank handle, universal for most brands of bit drive tools on the market. 118° SPLIT POINT TIP: Allows you to cut faster throughout multiple uses,and prevent walking. This product is a double-edged step drill. The larger the diameter is, the higher the power, the greater the torque, the lower the speed (100 ~ 800r / min) of the machine and the lower the temperature. It is necessary to have the conditions of large torque, low rotation speed (