... ''-11 thread 3.Never tip off 4.Side protecte Fast and Smooth Drilling Diamond Hollow Drill BitFeatures:Stone/Tile Core ... for core drilling of concrete, asphalt, brick, block and pavers, fast cutting speed, laser welded, good life.Supreme Concrete Core ... block, masonry, and tiles. Barrel vents allow easy removal of cutting debris.Details: Quality control: Factory: Fast and Smooth Drilling Diamond ...