Klingspors' (pressure sensitive adhesive) discs are made of full resin bonded Aluminum Oxide, heavy cloth backed material along with an adhesive that holds fast yet does not gum up your backing pad. Ideal for production situations that require discs to hold fast at high speeds and for repetitious, single-grit sanding of flat surfaces. Their competitors often use inferior materials or scrap in the manufacture of their discs. KLNGSPOR only uses only top quality industrial goods. You get an extended grit range so that you can pick the perfect finish every time. Each pre-glued disc attaches in seconds; simply peel off the release paper backing, stick, and sand. These discs are manufactured from premium Aluminum Oxide material which is suitable for use on all ferrous metals, hardwoods, leather, aluminum, brass, bronze, stainless steel, and most alloys. Specifications: Aluminum Oxide Closed coat Resin bonded Cloth backing Sticky back - PSA (pressure sensitive adhesive) Pack of 4