30 Inch Stick On PSA Metal Grinding Zirconia Sanding Discs. Heavy Y weight Cloth sticky backing. High quality and long lasting industrial abrasive sanding discs (blue/green colored) works great on hardwood, ferrous metals (aluminum, titanium, etc.) and grinding and beburring of ferrous metals (steel, cast iron, carbon steel, tool steel, stainless steel, nickel alloy, etc.). Closed Coating provides a smooth and balanced sanding finish. Resin over resin bonding. Discs are precisely stamped and bonded with an industrial grade stick on backing. Dry applications only. Assembled in USA.