3/8" Porcelain Tile Bit & 5/32" Pilot, Unique Point Grinding, More Flute Capacity, Chrome Vandium Shank, Porcelain Plus Is Ideal For Drilling Porcelain Tiles Up To A Scratch Hardness Of 8, Due To The Unique 4 Face Point Grinding The Drill Bit Will Not Walk, Diamond Ground Porcelain Plus Cuts Clean Holes With Very Little Or No Chipping, To Extend The Life Of The Bit, Let It Cool Down For Several Minutes Between Each Hole.