The CRL Diamond Grinding Bit produces a round edge on 3/16" and 1/4" (5 and 6 mm) glass. This top quality bit edges cut-outs quickly and efficiently while reducing the risk of cuts. Diamond coated edge grinds glass edges smoothly. Great for doing touch up work on the jobsite. The diamond grit is 220. Use Diamond Tool Coolant to prevent heat build-up and prolong bit life.