Fiber Disc Abrasive Type Coated Abrasive Material Zirconia Alumina Backing Material Fiber Backing Weight X Grit 50 Overall Diameter 4 1/2 in Series BlueFire F826 Maximum Operating Speed 11 000 RPM Resistance Properties Tear Connector Size 7/8 in Connector Type Unthreaded Hole Color Blue Grade Coarse Package Quantity 25