Feature:-Instructions for use:-Glass drilling device is installed in the use of ordinary hand drill (electric drill to speed better),because this hole is not the central positioning of the drill bit, be careful when operating,let the hole at a slow slow access to glassUseless side of the hole out of a crescent, and then put a bit is used to locate the crescent, so you can successfully complete the hole operation.-Note that when the hole in the speed can not be too fast, must be slow, in the process of opening the hole must be added water cooling device.Specifications:Product name: Drill BitMaterial: DiamondsColor: SilverLength: 50mm/1.96"Drilling size: 3/5/6/8/10/12/16/18/20/30/40/50/60/70mmPackage Include:14x Drill Bits