Diamond Granite Polishing Pads 4" inch Wet/Dry Set of 12+1 Backer Pad Best Value Concrete Marble toolsmart damo 12 Pcs of 4 Inch Diamond Polishing Pad (3mm Thick) for concrete stone and 1 backer. 12 Pads are: 3 X Grit 50, 2 X Grit 100 200, 1 X Grit 400 800 1500 3000 10000. 1 Pc Rubber Velcro Backer (5/8" Thread arbor). Backer has water feed hole, wet polishing no problem. Remind: Velcro Backer's max capacity is 5000RPM. Please don't use it with high speed grinder.