1/4" Course Twofers Grinder BitsAanraku TWOFERS 1 4 inch 120 course grit glass grinding bits (2 bits per package) Two Superior Quality Bits at One Value Price Aanraku's Twofers Grinder Bits offer superior quality at a low cost. The diamond abrasive grinding surface is double plated for strength, durability and long life. Diamond coat guaranteed not to peel! 100 120 diamond mesh grit and a small 1 4" diameter. Use it to quickly and aggressively grind away at the glass. Fits Gryphon,