RX-20 Hard Floor Brushes for medium duty Suitable for Medium Duty (MD) cleaning of stone, slate, terrazzo, tile or concrete floors. This attachment is also ideal for one-step stripping of resilient floors. The brush area is tufted with green .050 nylon fiber impregnated with 80-grit silicon carbide. 15" Diameter block, Five (5) vacuum pick-up tubes and Three (3) #2 S/S high- pressure solution jets. The brush on this attachment replaces brown and black pads and will outlast them more than 100 to 1.