Park Tool CB-4 is a 100% biodegradable natural plant-based degreaser formulated for use in the CM-5.3 Cyclone Chain Scrubber CM-25 Professional Chain Scrubber or with a scrubbing brush as a general purpose degreaser. When used with a chain cleaner CB-4 gets bicycle chains clean inside and out so they’re good as new. Will not harm alloy plastic rubber or carbon fiber parts so it’s safe to use for cleaning cassettes chainrings pulleys or any other component that accumulates muck and grime.