Remind: The 5/8-11 Female Thread Arbor velcro backer/pad holder are with water feed hole, can be used for wet polishing. Remind: velcro backer’s max capacity / velocity is 5000RPM, please don’t use it with high speed polisher/grinder. 29 Pieces of 5 / 125MM Diameter Pad for granite marble concrete travertine they can be wet or dry use. Wet use make its life longer. And 1 Piece 5 Backer. (5/8-11 female thread arbor). The 29 Pads are. 6 Pieces X Grit 50 100. 4 Pieces X Grit 200 400. 3 Pieces X Grit 800. 2 X Pieces X Grit 1500 3000 6000. 3.2mm thickness. Recommend 2800 – 5000 rpm (grinder or polisher speed must be lower than 5000 RPM). Wet or dry use (wet use recommended).