diamond Flexible backer: 1) Fixed on hand polisher. 2) High quality foam backer. 3) Flexible design. 4) Good price Diamond Flexible backerItemDiameterInner diameterGSFB-030080mm(3")M14,M16,5/8"-11GSFB-0400100mm(4")M14,M16,5/8"-11GSFB-0500125mm(5")M14,M16,5/8"-11 diamond Flexible backer