4 Piece, Natural Stone, Tile Bit Set, Consists Of: 1/8", 3/16", 1/4", 5/16" Bits, Multi-Grind Head, Designed With Multiple Cutting Edges For Harder Tile Materials, Fast Drilling In Hard Materials, Specialized Carbide Tip, Centers For No-Skate Drilling & Greater Ease Of Use, High Quality Carbide Material, Provides Longer Life In Hard Materials, 3 Flat Shank Offers Outstanding Bit Grip To Avoid Slippage, Engineered For Use In Natural Stone Tile, Slate, Granite & Other Specialty Tile Materials Specialty Tiles That May Be Harder Than Normal Tile, Not Recommended For Use On Porcelain Tiles, Compatible With Hammer Drills.