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 hexagonal shank allows a stable hold and quick release in the electric drill. Dimension: Set of 10 drill bits with 7 different sizes: 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. Four-corner sharp chamfer design, easy and stable positioning, faster drilling speed, better stability, low fluctuation frequency and high efficiency. Application: Ideal for drilling ceramic tile, glass, marble and mirrors. When drilling hard materials, please use water for lubrication, good cooling can extend the service 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 bits for drilling hard tiles. Tungsten Carbide Tipped: The bit features a tungsten carbide tip for longer efficiency and life. Professional Alloy Steel Grade - Smooth and precise drilling in ceramic tile, marble, mirrors, glass, aluminum, concrete and wood. For DIY and home decor enthusiasts, it's also an essential tool for drilling glass and other hard, fragile work surfaces.