Features: 100% High quality and Brand new. This product uses advanced natural diamond material, with a special enhanced coagulation treatment from electroplating sand suction hole neat, smooth, no broken edges, etc., is the efficient construction, installation hole of choice. This section openings optimum glass openings, tiles can be opened, but just open a few holes in the opening, please add water, it will extend the life. The product is installed on a professional drill or electric drill, bench drill. Rpm 800-1000 rpm or so, you must add water cooling holes during operation. Use: apply to work openings fast glass, plastic sheeting, wood and other products. Size: 3mm / 5mm / 6mm / 8mm / 10mm / 12mm / 16mm / 18mm / 20mm / 30mm / 40mm / 50mm / 60mm / 70mm Package Includes: 14pcs Diamond Coated Hole Saw Drill Bits NOTE: 1 After opening installation, commissioning idling should observe whether the beating, then normal operation, the best results 2 Into the hole to have a smooth time, please do not exert pressure on the side and curves spud 3 Have enough openings for cooling and lubrication to reduce wear and coating products off 4 Non occurrence of high temperature drilling dry rub, causing severe wear affect the results 5 The operator must wear safety protective equipment to confirm safe operation .6. Please note that the new type and old type of this product will be sent randomly, and make sure you will not mind before ordering.