Flap Disc, Abrasive Type Coated, Abrasive Material Zirconia Alumina, Grade Fine, Connector Size 1/4 In.- 20, Connector Type Unthreaded Hole, Flap Disc Type Type 27, Overall Diameter 3 in, Series Heavy Duty, Backing Material Fiberglass, Grit 120, Maximum Operating Speed 18,000 RPM