1. 7 inch back holders are designed to fit diamond polishing pads, Max RPM 8500.2. Backer Pads with backing could be attached to any polishing pads easily and allows for a fast switching between different grit size.3. Connect a back holder to the polisher, and attach a polishing pad to the back holder.4. Using a thicker J-Hook design made from a more heat resistant material, and implementing a stronger adhesive.5. Please use with power tools with M14 thread spindle. (thread spindle is not included here) Specification:Product Name: Backer PadMaterial: Plastic, SpongeDiameter: 180mm / 7 InchThread Size: M14 Female Thread; Max RPM: 8500Package Content: 1 x Backer PadsWeight: 143g; Color: Black, Yellow