The pad holder’s arbor is 5/8-11 female thread. Pad Holder’s max capacity / velocity is 5000 RPM. Please do not use it with high speed grinder or polisher. This package carries (a)-(d). (a) 1 Piece of 7″ / 7 Inch (Non Threaded, inner hole diameter 7/8″-5/8) Diamond Double Row Grinding Cup Wheel for concrete stone surface grinding. And 1 set of Lock ring nuts and wrench (fits 5/8-11 Thread spindle grinder or polisher). (b) 1 Pieces of 7″ / 180mm Diameter (5/8″-11 Female Thread arbor) Velcro Backer / Pad Holder Remind: Rubber Backer’s max capacity / velocity is 5000 RPM. Please don’t use it with high speed grinder / polisher. (c) 9 Pieces of 7 / 180mm Higher Diamond Concentration More Long Lasting Honeycomb wet dry (wet use recommended) Polishing Pad for granite marble concrete. 1 X Grit 30 50 100 200 400 800 1500 3000 10 000. (d) 30 Pieces of 7 Inch / 180 MM Silicon Carbide Oxide Coarse Grit Sandpaper for metal, wood, stone, granite, marble, concrete, jade, rubber, fiberglass, rust paint remove, deburring. 3.2mm thickness. Recommend 2500 – 5000 rpm(grinder or polisher speed lower than 5000 RPm). Wet or dry use (wet use reommended).