Remind: The TWO velcro backer/pad holder are with water feed hole, can be used for wet polishing. Remind: Rubber velcro backer’s max capacity / velocity is 5000 RPM, please don’t use it with high speed polisher/grinder. This package carries (a)-(c). (a) 200 Pieces of 5 Pad for granite marble concrete travertine. 20 X Grit 15 30. 30 X Grit 50 100 200 400. 10 X Grit 800 1500 3000 6000. (b) 1 Piece 5″ rubber Backer (5/8″-11 female thread arbor). (b) 1 Piece 5″ aluminum Backer (5/8″-11 female thread arbor). Recommend 3500 – 5000 rpm (grinder or polisher speed must be lower than 55000 RPM). Wet or dry use (wet use recommended).