FC 28-521C 28" 18 Single Row .035"/180 Mid Grit Cylinder Scrub Brush for Factory Cat / Tomcat 28, 2800C, 29, 3000C, 350C, 30 (MiniMag/Magnum/GTX30) Scrubbers. A middle grit scrub brush for general duty scrubbing tasks. Narrow .035" diamater Tynex-A Nylon filament impregnated with 180 grit silicon carbide granules for reaching small cracks and into grout lines. Equivalent to Midi-Grit. Fits Factory Cat and Tomcat 28, 2800C, 2800EX, 29, 3000C, MiniMag 30, Magnum 30, GTX 30 and 350C scrubbers which require two 28" cylindrical scrub brushes (Listed as a 30C Old Style - 30" scrub path with brush overlap). These are the OLD style scrub brushes with the slotted drive system (newer style is a "star" drive with six notches). These are for units with serial numbers BELOW 50000. Please check your unit before ordering. Two brushes required per unit. Priced each. Replaces Factory Cat / Tomcat 28-521C, Carlisle/Flo-Pac 36770728, 770728