GP12609 Hook and Loop Rotary Backing Pad with 5/8''-11 Thread, Sanding, Polishing Backer / Diameter 4.5 inch Diameter: 4.5 inch Thread size : 5/8'' - 11 Hook and Loop fastener (velcro type) 15mm Foam Flexi Layer makes this pad ideal for sanding or polishing curved or flat surface Recommended for use with rotary device / Max RPM: 2500