This 22″ Soft Black Disk Scrub Brush for SUNMAX RT50, RT50+, RT50D, RT50D+, RT50AC, RT70, RT70+ Floor Scrubber Machines. . Made from durable polypropylene and designed to be gentle on surfaces, this brush ensures the highest quality floor care cleaning. Medium gauge brushes (19 – 21 gauge), good for all-purpose cleaning on most floor types, including tile, grout, and wood.