?Premium ceramic alumina and zirconia alumina abrasive blend for excellent performance and efficiencies on mild carbon steel and ferrous metal/cast iron applications?Type 27 have a flatter angle and are best used on flat surfaces for blending and smooth finishing?Plastic backing plates add some conformability and are trimmable?Medium/60 grit for blending and deburring?Poly/cotton backing combination for good cut rate and finishing?Flap discs are versatile grinding and finishing tools having four main components: abrasive flaps, flap density (how the flaps are stacked), backing plate (flat or conical shape), backing plate material (fiberglass/resin, plastic, aluminum). All flap discs have flaps that are overlapped and glued to the backing plate. The flaps wear during use exposing new abrasive grain. The different variations of the components above provide a variety of choices ranging from heavy stock removal to blending to finishing. Flap discs are designed for portable grinder applications and can be the preferred choice over depressed center wheels or fiber disc.