Material:: The drill bit is made of high quality heat treated high carbon steel. The titanium alloy coating has high hardness, good wear resistance and durability. Outstanding Design:: The drill has a three-point design, and the tricuspid valve is better centered, without deflection, and can drill quickly and accurately. High Quality:: Heat treated high carbon steel, titanium alloy coating has high hardness, good wear resistance and durability. Excellent cutting capacity. Value Set:: The drill bit set includes 7 different size drill bits and 1 wrench, the sizes are: 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm, the diameter of the chamfer is 15.8mm, which can meet all your demand. Versatile:: suitable for granite, ceramic tile, glass, square, ceramic, ceramic tile, PVC, rubber, plank, hardwood or wood floors, etc. Suitable for bench drill, drill press hand and the conventional drill.