SIZE: 5pcs diamond drill bits(6mm 1/4", 8mm 5/16", 10mm 3/8", 12mm, 14mm, each size 1pc) APPLICATION: Dry drilling for Granite, Tile, Ceramic, Marble, Stone, Porcelain, Masonry. Use water for longer time. COOLING WAX: 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. Diamond material upgraded, can drill 10-15 more holes than ordinary drill bits. NOTE: The cross hole opener is to provide accurate positioning for diamond bit, not recommended for drilling；Hand drill at 2000-5000RPM, the slower the shorter the life.