High quality diamond drill bit set that won't rust, cuts quickly - Made from high strength carbon steel with nickel plated surface makes these drill bits durable and precise; drill bit tip head is made of coating 80 grit diamond, which is uniform; it helps increase drilling speed and sharper than other ordinary hole saws.10 pieces of most used size - Includes the following diameters: 8mm, 10mm, 12mm, 14mm, 16mm, 18mm, 20mm, 22mm, 25mm, 50mm. Using laser marking, the size will meet most of your different needs.Application: Suitable for drilling holes on glass, marble, tiles, pots, fiberglass, porcelain, tiles, ceramics, slate, granite, etc. Works with all electric drills and drills percussion.Nice Design - Center Holes and Side Holes Help Remove Trash Easily; nickel plated surface prolongs life and improves corrosion resistanceNotice: When cutting hard materials, it is important to ensure that the bit stays cool to prevent damage to the material being drilled and premature wear of the bit. Water is needed for lubrication when drilling, which which can extend the service life of the drill bit set.