Remind: The 5/8-11 Female Thread velcro backer/pad holder are with water feed hole, can be used for wet polishing. 30 Pieces of 5 Pad for granite marble concrete. And 1 Piece 5 Backer. (5/8-11 female thread arbor). The 30 Pads are. 4 Pcs X Grit 15. 6 Pcs X Grit 50. 4 Pcs X Grit 100 200 400. 2 Pcs 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).