High Quality: The drill bit is made of professional alloy steel. High hardness, strong and durable. It has good wear resistance and can be used longer than ordinary steel drill bits. The hexagon shank allows for stable holding and quick release in the drill. Dimensions: Set of 10 drill bits with 7 different sizes: either 1/8? (3mm), 5/32? (4mm), 3/16? (5mm), 1/4? (6mm), 5/16? (8mm), 3/8? (10mm), 1/2? (12mm) to meet your different needs. Sharp chamfer design at four corners, easy and stable positioning, faster drilling speed, better stability, low fluctuation frequency and high efficiency. Application: Ideal for drilling ceramic tiles, glass, marble and mirrors. When drilling hard materials, please use water for lubrication, good cooling can extend the life of the drill bit. Please try to keep the drill vertical and use water or coolant for lubrication when drilling. Do not use these drill bits to drill into hard tiles. Tungsten Carbide Tip: The drill bit features a tungsten carbide