Park Tool RBS-25 Replacement Brush and Sponge Cartridge for CM-25 The Park Tool RBS-25 Replacement Brush and Sponge Cartridge for CM-25 is designed to keep your chain scrubber working efficiently. This cartridge is a perfect fit for the CM-25 Professional Chain Scrubber, ensuring your bike's chain stays clean and well-maintained. With the Park Tool RBS-25 Replacement Brush and Sponge Cartridge for CM-25, you get: Two rotating brushes for thorough cleaning Two sponges to absorb excess grime Two wicking pads to help with drying All components come pre-installed in a composite cartridge, making it easy to snap into place and get back to cycling in no time.