Fast Grinding 100% Polyester Backed Discs in Five Grits from 60X to 400X in Two Popular Sizes Special Sizes and Grits Available on Request Several Popular Sizes: 5", 6" and 7" (127, 152.4 and 177.8 mm) Our CRL Silicon Carbide Sanding Discs come in several diameters to fit most popular brands of disc sanders. They have a 100 percent polyester backing that lets you use them wet or dry. Grit: 60X Diameter: 5 in (127 mm) Center Hole: 7/8 in (22.2 mm) Additional Product Information: Most Popular Grits for Glass, and Examples of Their Use: 60X - Extra Rough: Fast Glass Removal (Mitered Edge) 80X - Rough: Quick Contouring (Auto Glass Edge) 120X - Smooth: Seaming and Polishing (Desk Top Edge) 220X - Extra Smooth: Fine Frosted Finish (Glass Shelf Edge) 400X - Fine: Satin Finish (Opaque Edge) 50 discs per box.