"The colored bit that corresponds to its grit!" The Gel Bit accommodates every type of stained glass grinder. These affordable and attractive bits are designed with the same performance as traditional grinding bits. The Gel Bit features a high-quality diamond grit available in 1" (25.4mm) and 3/4" (19.05mm) diameters.  This listing is for a 3/4" STANDARD (100/120) grit.