2 pcs. 38mm and 45mm Porcelain Diamond Drill Bits Always use lubrication (water), otherwise the diamond drill bit will burn Start a diagonal hole, make a circular trace, then hold the drill bit straight Size: 1 1/2 in (38 mm) / 1 3/4 in (45 mm) Delivery quantity: 2 pieces Product color: silver Product size: 38mm+45mm Note: manual measurement, please allow 1-3cm error Replacement for: Diamond Coated Hole Drill Bits are the perfect replacement to make clean and accurate holes on glass, tile and marble. Can be used with a standard electric drill Simple to use: Coated hole cutters are easy to use, high quality, good performance, long service life Application: This diamond drill eliminates a full circle in glass, tile, marble, granite, etc. Good quality: Coated hole cutters provide excellent performance and cut resistance. High quality, good performance and can have a long life if used properly. Note: When diamond drilling, water (lubricant) should be added when replacing the drill to prevent burning of the drill bit and materials.