Higher efficiency with the 3 teeth cutter head. It is more accurate and safer to use these drill bit sets in a drill press. The head is good at removing the debris and working efficiently with radian curved design. The tip is specially designed to cut through hole cleanly, great for boring concealed hinges and door locks. This Forstner Drill Bit is high hardness, wear resistance, good toughness, heat and corrosion. Applicable to various gypsum, plastic, wooden board, solid wood, artificial wood, indispensable woodworking gadget. Easy to install and use, suitable for chuck greater than or equal to 10mm electric drill, bench drill, high power electric grinding, pneumatic drilling, magnetic drill. Specifications: 15mm Material: Carbide Drilling Diameter: 15mm / 0.59 inch Shank Diameter: 7mm / 0.28 inch Total Length: 80mm / 3.15 inch 20mm Material: Carbide Drilling Diameter: 20mm / 0.79 inch Shank Diameter: 7mm / 0.28 inch Total Length: 80mm / 3.15 inch 25mm Material: Carbide Drilling Diameter: 25mm / 0.98 inch Shank Diameter: 8mm / 0.31 inch Total Length: 80mm / 3.15 inch 30mm Material: Carbide Drilling Diameter: 30mm / 1.18 inch Shank Diameter: 8mm / 0.31 inch Total Length: 80mm / 3.15 inch 35mm Material: Carbide Drilling Diameter: 35mm / 1.38 inch Shank Diameter: 8mm / 0.31 inch Total Length: 80mm / 3.15 inch 40mm Material: Carbide Drilling Diameter: 40mm / 1.57 inch Shank Diameter: 9mm / 0.35 inch Total Length: 80mm / 3.15 inch Package Contents: 6x Hole Saw Bits 6x Plastic Package Boxes Warning Tips: The temperature of these materials: wood, plastic, plywood etc. will get a kind of high when using this drill bit, please add some WATER or COOLANT to avoid them from getting smoke. WARNING: This product can expose you to Lead, which is known to the State of California to cause cancer. For more information go to www.P65warnings.ca.gov.