Diamond Polishing Pads 7 inch Wet/Dry 12+1 Pieces Set Pad 3mm Thick Granite Concrete 12 Pcs of 7" Diamond Polishing Pad (3mm Thick) for concrete stone and 1 backer. 12 Pads are: 2 X Grit 50 100 200 400 800, 1 X Grit 1500 3000. 1 Pcs Rubber 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.