Heavy Duty 7 inch abrasive disc with velcro backing made from semi open web that contains extra course silicon carbide through the entire thickness of the disc. Outlasts most other discs. Discs are 5/8 inch thick and come ready to mount onto velcro backup pad. For use with Aargo Tools part # 380002 7 inch back up pad and Aargo Tools part # 904059 7 inch Air powered Sander or part # 904019 7 inch Electric Sander which can be ordered separately.