Size: Total 10 pieces, 8 pcs dry diamond drill bits (1/4" 6mm), round shank and 2pcs Carbide Drill bit (1/4" 6mm). Application: For Granite, Tile, Ceramic, Marble, Stone, Porcelain, Masonry. Use water for longer time. Wax inside: For cooling,our Diamond Tipped Drill Bits have wax cores built-in which automatically absorb and dissipate heat as you go. Vacuum Brazed technology: Higher efficiency, faster working speed, longer service life. Note: Used for hand drill and bench drill,Hand drill at 2000-5000 RPM, the slower the shorter the life.