Features:Made of premium diamond material with high hardness, durable in useStrong opening performance, fast drilling speed, smooth drilling without seamless Application: Suitable for drilling marble, concrete, granite, tile, glass, etc Adopting high quality diamond brazing technology, the tooth blade is sharp, the opening hole is smooth without broken edges, and there is no tremor phenomenonChip removal hole design, conducive to chip removalCan be installed on the electric drill easily for labor-savingSpecification:Material:diamondSize:16mm / 0.6in,35mm / 1.4in(Optional)Weight: 37 g-85 / 1.3-3 oz(approx.)Note:1. The hole opener is installed on the electric drill. Since this kind of hole opener does not have a center positioning bit, please operate it carefully and pay attention to safety2.Speed can't be too fast, keep slow speed3. Keep adding water for cooling. Dry drilling is strictly prohibited, otherwise high temperature friction will affect the use effect