Upgraded Dry Drilling Design : Diamond Drill Bit integrated with wax lubricant inside which melts while dry drilling and cools the cutting surface; Water can be used as additional cooling to prolong the life of the bit. Surface plating can prevent the drill bit from rustingWildly Application: dry diamond drill set can be applied for drilling clean holes to hard materials, which especially fits well for tiles, porcelain ground, granite ceramic glass mirror marble stone masonry brick and so on; Note: not applicable to wood. Widely Compatibility: drill is designed in Hexagon , which is compatible with most machines, such as hand drill, angle grinder, bench drill, also can be matched with side flutes help to remove debris and drill holes smooth and fast; Depth mark is also useful for precise project. : Hexagon colour: blackMaterial: Diamond Coated,The measurement allowed error is +/- 1-3cm.