FC 19-421D 18" Pad Driver Assembly for Factory Cat and Tomcat Floor Scrubbers. An 18" diameter molded plastic brush block with 1/2" short trimmed polypropylene. The short trim poly digs into and holds your floor pad securely to the brush block with the aid of a pad centering device or "pad grabber". This two piece pad grabber is included with the assembly. 18" diameter plastic block 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). Designed to hold your 18" or 19" diameter floor pads. 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 pad drivers per unit. Factory Cat 550D requires three pad drivers. Priced Each. Replaces Factory Cat 19-421D. Our Part Number FC 19-421D