GP12621 Hook and Loop Rotary Backing Pad with 5/8''-11 Thread, Sanding, Polishing Backer/Diameter 5 inch Diameter: 5 inch 30mm PU Flexi Layer make this pad excellent for sanding and polishing curved or flat surfaces Thread Size : 5/8''-11 Hook and Loop Fastener (Velcro Type) / Max RPM: 6500