3 X 21 Inch Standard Metal Sanding Belts, 8 Pack. Aluminum Oxide (A/O). Closed coat, X weight Cloth backing. Sold in packs of 8. High quality and long lasting all purpose industrial abrasive sanding file belts provide an even finish on hardwood, solid surface, and non ferrous metal (Aluminum, Copper, Titanium, Nickel) when used with pneumatic and electric file belt sanders. Closed Coating provides a smooth and balanced sanding finish. Resin over resin bonding. Bi-directional tape joint. Assembled in USA.