Shape:Round Abrasive:ZA Bonding Agent:Resin Hardness:Medium Viscosity:Proper Size:4'' Size:4 inch Bore:5 8 inch Flap size L:24mm Flap size W:16-18mm Max Operation Speed RPM:15300 Max Operation Speed M S:80 Abarasive:normal treated ZA Grit:24,36,40,60,80,100,120 Backing:fibreglass, nylon Product name:Zirconia aluminum flap disc with good quality