FC 40-521C 38" 18 Single Row .035"/180 Mid Grit Abrasive Cylinder Sweep/Scrub Brush for Factory Cat 420, 430 Riding Floor Scrubbers. A middle grit scrub brush for general duty scrubbing tasks. Narrow .035" diameter Tynex-A Nylon filament impregnated with 180 grit silicon carbide granules for reaching medium and small cracks and into grout lines. Equivalent to Midi-Grit. Usually blue or grey 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 23-421C, .035" Midi-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 40-521C. Our Part Number FC 40-521C