Non-Woven Depressed Center Disc, Abrasive Material Silicon Carbide, Grade Fine, Overall Diameter 4 1/2 in, Series EXL-UD, Maximum Operating Speed 13,300 RPM, Connector Size 7/8 in, Connector Type Unthreaded Hole, Abrasive Type Non-Woven, Color Gray, Disc Shape Type Type 27, Resistance Properties Smear