4" X 21" Abrasive Sanding Belts (grinding belts). 100 grit. Zirconia Alumina (Z/A). Closed coat, Heavy Y weight Cloth backing. High quality and long lasting industrial abrasive sanding belts (blue/green colored) work great on hardwood, ferrous metals (aluminum, titanium, etc.) and ferrous metals (steel, cast iron, carbon steel, tool steel, stainless steel, nickel alloy, etc.). Super Heavy duty Y-wgt material provides extra strength for working with metal grinding and deburring. Resin over resin bonding. Bi-directional tape joint. Dry applications. Assembled in America.