FC 19-421N 18" Soft Nylon Scrub Brush for Factory Cat and Tomcat Floor Scrubbers. General duty and long lasting soft .016" diameter level white or black Nylon. These soft Nylon scrub brushes are great for light duty scrubbing of some polished hard surfaces and most delicate medium to soft surfaces. These soft nylon brushes will not harm polished flooring found in some plants and auto dealership showrooms. For a slightly stiffer Nylon for most surfaces such as grit impregnated epoxy painted floors, use our .030" diameter Nylon (FC 18-421N30). 18" diameter plastic block (19" scrub path) with an 8-point clutch plate (Please check your model for the proper number of points. We offer a 6 point and 8 point clutch plate). Some of these models also use cylinder scrub brushes instead of disc brushes. Please check your existing brush set up before ordering. Fits Factory Cat and Tomcat floor scrubber models including Factory Cat 38, 40, 40HD, 550D and Tomcat 3700D. Most machines require two brushes per unit. Factory Cat 550D requires three brushes. Priced Each. Replaces Factory Cat 19-421N. Our Part Number FC 19-421N