all media for wet grinding polishing with velco backing to be used on concrete double power trowel machines, see "www.concria.com" system, media applied in 6-7 steps on hardened concrete of a total floor area of 60,000 m2 to be started with 70 grid metal bound - then followed with resin bound 50 grid - 100 grid - 120 grid - 200 grid - 400 grid - 800 grid,