Diamond Polishing Pad 3" inch 355 Pieces and 2 Rubber Backer Granite Stone Concrete Marble 355 Pcs of 3" Diamond Polishing Pad for concrete stone and 2 backer. 355 Pads are: 15 X Grit 30, 60 X 50 100 200 400, 30 Pcs X Grit 800 1500, 20 Pcs X Grit 3000 Buff. 2 Pcs of 3" Rubber Backer (5/8" Thread arbor). Remind: Rubber Backer's max capacity is 5000RPM. Please don't use it with high speed grinder.