Diablo 3 inch x 21 inch 50 Grit sanding belts include break through innovations that improve performance and it extend sanding life and increase productivity. Featuring a premium zirconium blend with these belts remove material faster than other sanding belts and offer an extra long sanding life. Recommended use for extra heavy stock removal, planning and sandingClog-Shield, a proprietary blend of grinding agents that reduce pitch build-up and cloggingEndura-Bond, a specialized high strength resin provides superior grit-to-backing bond for extreme durabilityFor use on belt sanders in wood, metal and plastics