C.R. LAURENCE CRL3X21120X CRL 3" x 21" 120X Grit Glass Grinding Belts for Portable Sanders - 10/Bx. CRL Glass Grinding Belts have been an industry favorite for years, and our alliance with a major abrasive manufacturer allows us to bring you high quality belts at low prices. Cost-efficient packaging techniques let us give you better value in all sizes and grits from 36X (Super Coarse) to CORK (Polishing) on a 100 percent polyester backing that works either wet or dry. For polishing, our cork belts provide a smooth luster finish where desired. We even offer custom sizes to meet your needs.. Part Numbers Variations: CRL3X21120X