COMBICLICK® Surface Finishing Set - 4-1/2" Diameter Discs, 5/8-11 Threaded Backing PadPferds Combiclick System greatly improves upon existing 7 8 resin fiber discs. I used to hate how the center clamping nut would always get in the way and how easy it was for the disc to snag and tear out. Heres what else makes the Combiclick system a pleasure to use: Tool less quick change Really low grinding angle (down to 3 degrees vs 15 for the other systems) Flexible edge conforms to corners Does not tear out as easily as fiber discs with a