Rugged Scrim Backing Of Paper Sanding Disc’s Embedded Loops Fasten To The Embedded Hooks On Sander Face. The Hook & Loop Backing For Quick And Easy Disc Change. Lasts 3x Longer Than Conventional Aluminum Oxide And Has Consistent Finish And Superior Cut Rate. Non-Pigmented, Water-Based Zinc Stearate (Anti-Clog), Open Coat For Reduced Loading And No Finish Contamination.