Silicon Carbide Grit Even-Run Seam for Smooth Flowing Action CRL 3M Duo-Glass high quality belts feature silicon carbide grit bonded to a strong, waterproof, cloth-backed belt. An even-run seam produces a smooth flowing action for a great finish on glass. A belt trusted throughout the industry and known for its quality and reliability. Five belts per box. Five Standard Sizes Available: 3 x 21 inch (76 x 533 millimeter) 3 x 24 inch (76 x 610 millimeter) 4 x 24 inch (102 x 610 millimeter) 4 x 106 inch (102 x 2,692 millimeter) 4 x 132 inch (102 x 3,253 millimeter)