4" inch 100mm Velcro Diamond polishing pad holder or backer this allows Velcro backed polishing pads connect in little or no time to polish marble, granite and all natural stone. It connects to grinder and many different machines with the standard 5/8-11 Thread Arbor. Rigid aerodynamic shape allows maximum performance with your polishing pads. | For use with 4" Diameter Pads and will work with 3" Pads as well. US-BASED CUSTOMER SERVICE: Available by chat, email, phone, or visit us at our customer service center in La Crosse, WI.