The HP RM1-5224-000CN separation roller assembly is a replacement part for the envelope feeder in supported HP LaserJet Enterprise 600 printers. It is identified specifically as the feeder’s separation roller, a distinct component from its paper-feed and pickup rollers.
The retailer lists compatibility with the M601, M602, M603, M604, M605 and M606 models. This part is intended for the envelope-feeder assembly in those listed printers.