Stadea 4" Rubber Backing Pad/Rubber Backer Pad with Flexible Rubber Body for Stone Edge Polishing - Arbor 5/8" 11 4" Rubber Backing Pad made with super premium grade rubber, semi-flexible backer perfect for counter edge polishing Premium grade/quality for stronger bond with attachments Brass arbor with 5/8" 11 Thread Diameter 4" or 100 mm Max RPM 4200