FC 40-521S 38" 18 Single Row .050"/80 Heavy Grit Abrasive Cylinder Sweep/Scrub Brush for Factory Cat 420, 430 Riding Floor Scrubbers. An aggressive abrasive cylindrical scrubbing brush for heavy duty scrubbing or stripping jobs. Long lasting .050" Tynex-A Nylon filament impregnated with 80 grit silicon carbide granules. Equivalent to Tough Grit. Usually black in color. 38"L x 9"OD. Fits Factory Cat 420-C and 430-C cylindrical scrub brush riding scrubbers. Some units (420, Disc) require two 22" disc brushes instead of cylinder brushes (use two 23-421SS, .065" Super Grit equivalent or 23-421S, .050"/80 Tough Grit equivalent disc brush - 21" block diameter). Please check your unit before ordering. Two cylindrical brushes create a 42" wide scrubbing path. Two brushes required. Priced each. Replaces Factory Cat 40-521S. Our Part Number FC 40-521S