​product name：alumina flap disc basic information： type：T27/T29 grain：alumina backing：heavy X-wt polystyrene cloth cover：7/7+1/9/9+1 fiberglass cover outer dia.：4"/4.5"/5"/7" core：5/8" or 7/8" grit:40/60/80/120 feature： 1.sharp&fast grinding 2.lager&thickening falp，high work efficiency 3.uniform sanding&polishing effect 4.good synchronization，long lasting&durable application： rust, paint, ferrous, and non-ferrous metals, wood and plastics