TILE MARBLE GRANITE PORCELAIN MASONRY CAST IRON HARDENED STEEL Designed for Drilling Marble, Granite, Porcelain Tile, Hard Metal, Plastic, Wood, Masonry Percussion or rotary-only, the Groo-V Tip bit makes holes in almost all materials! Engineered for drilling hard materials, these specialized Ram Tip Bits have a serrated carbide tip, which penetrates faster - up to 50% faster than standard masonry bits! Point Diameter: 5/16 in (8 mm) Shank Diameter: 1/4 in (6.3 mm) Overall Length: 6 in (152.4 mm) Drilling Depth: 4 in (101.6 mm) Minimum Order: 1 Each Note: A drill press - supported drill motor is recommended for drilling hard metal. Shank diameter 3/8" and larger have 3 flats on the shank to reduce the possibility of slipping in the chuck.