DeWALT DARB1G0305 4.5" 36 Grit High Performance Aluminum Oxide Fiber Resin Disc, 5 Count; High performance aluminum oxide grain allows disc to break down quickly, exposing new grain for faster removal. This proprietary material mix ensures a durable and long life. The tough fiber backing prevents tearing and allow for longer life. 5/8" 11 arbor discs use quick lock backing pads for quick disc changing.