UNITED ABRASIVES - SAIT 50224 7A-S FIBER DISC 4-1/2"" X 7/8"" 80 GRIT CERAMIC ECONOMICAL CERAMIC BLEND FIBER DISC CLOSED COAT. FAST AGGRESSIVE STOCK REMOVAL. RESIN OVER RESIN CONSTRUCTION FOR A STRONG BOND THAT IS RESISTANT TO HEAT AND MOISTURE. VULCANIZED FIBER BACKING FOR HEAVY DUTY SANDING.