4" dry diamond concrete polishing kit - Polishing Pads hook and loop backing pads set Professional Grade 4" Diameter Dry Diamond Polishing Pads 6 Pcs set for Granite, Marble, Concrete, Stone polishing, 1 pieces X Grit (50, 100, 200, 400, 800) and 5/8" 11 threaded 4" rubber backer. 1.2 MM high and flexible velcro backed Works great on Granite, Concrete, Marble and stones etc Optimal RPM 1800 Max RPM 3000 Optimal RPM 1800 Max RPM 3000, works with variable speed grinders polishers