Remind: The 5/8-11 thread velcro backer/pad holder are with water feed hole, can be used for wet polishing. Our 7 Inch Polishing Pad Thickness is 3.2mm. Not the 2.8mm or 3mm cheaper type. 32 Pieces of 7 / 7 Inch Higher Diamond concentration more long lasting Pad Honeycomb Pattern for granite marble concrete. And 1 Piece 7 Backer. The 32 Pads are. 6 X Grit 50 100 200 400. 2 X Grit 800 1500 3000 10000. Remind: velcro backer’s max capacity is 5000RPM, please don’t use it with high speed polisher/grinder. 3.2mm thickness. Recommend 3500 – 5000 rpm (grinder or polisher speed MUST BE lower than 5000 RPM). Wet or dry use, wet use recommended.