GP13403 GP-PRO100 MEDIUM Grade Sanding Disc for Glass, Silicon Carbide Abrasive Disc / 4.5-Inch (Pack of 10) Discs diameter: 4.5 inch / Pack of 10 Discs Constructed from top grade silicon carbide, with green velour backing for use with any Velcro backing pad GP-PRO100 Medium Grade for removing deep damage: sandpaper scratches, razor blades scratches, windows cleaner damage, scuffs from any glass surface. Recommended to use with electric rotary device ( drill, polishing machine ) at about 1500-2000rpm. For best results pre-polish process and final polishing process is required. Please check detailed product description for more information's.