Diamond Polishing Pads 4 inch Wet/Dry 14+1 Pieces Set Pad 3mm Thick Granite Concrete 14 Pcs of 4" Diamond Polishing Pad (3mm Thick) for concrete stone and 1 backer. 14 Pads are: 3 X Grit 50 100, 2 X Grit 200 400, 1 X Grit 800 1500 3000 buff. 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.