FC 28-521N 28" 18SR Soft Nylon Cylinder Scrub Brush for Factory Cat / Tomcat 28, 2800C, 29, 3000C, 350C, 30 (MiniMag/Magnum/GTX30) Scrubbers with Serial Numbers Below 5000. Soft .014" diameter Nylon filament for light duty scrubbing of polished concrete, marble, newer epoxy painted flooring or any other sensitive flooring. Equivalent to Nylon, Nylex. 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 28-521PS. Our Part Number FC 28521N