Item Type: Step Drill Bit Material: High Speed Steel Uses: It can be used in sheet metal processing, automobile industry, aviation industry, electrical machinery, workshop processing industry, etc. Shank Diameter: Approx. 6mm / 0.2in, 9mm / 0.4in Drill Size: 3/16in - 1/2in, 1/8in - 1/2in, 1/4in - 3/4in, 3/16in - 7/8in, 1/4in - (1-3/8in) Package List 5 x Step Drill Bit The larger the hole diameter, the lower the speed of the electric drill. The recommended speed is within 1000RPM. 1118 X type opening design will effectively prevent drill bit from slipping and ensure drilling accuracy. 2Incisive and wear resistant, has no burrs, promising efficient perforation and smoother chip removal. 3Ti plated surface with optical fibre marking, the clear diameter can be easily recognized at a glance. 4Ideal for processing workpieces with a hardness of 25 and a thickness of 2mm or less, such as aluminium plate, PV plate, and insulating plate. 5Can be used in sheet metal processing, automobile industry, aviation industry, electrical machinery, workshop processing industry, etc.