4-1/2X7/8 50 GRIT CGW Sanding Disc is as tough as it is versatile. This disc is perfect for general purpose metal grinding, and rust/scale removal, yet is the most economical disc in the fiber disc category. The Aluminum Oxide gain is the most commonly used grain in the industry, due to its superior resilience and wide range of applications. Excellent multipurpose sanding disc performance at exceptional value.