Designed for use by D-I-Yers, contractors and hobbyists on very hard or fragile materials such as porcelain tile, ceramic tile, stone, ceramics and glass. Diamond Core Drill Bits are premium specialty drill bits designed for drilling in hard abrasive non-ferrous materials. The electroplate bonded diamond drill bits have a superior design developed through extensive testing. Water is required for lubrication when drilling. Designed for drilling to depths of about _?. (Not for use on metals, concrete, masonry, or with impact hammer drills). The patented DiamondSure bonded diamond drill bit fills a major gap in the current retail drill bit product lines. They are designed to be an inexpensive solution to cleanly and quickly drill in hard and fragile materials where no carbide or other retail drill bit is able.