I am a bit anal about keeping my chain clean. I do 3.000+ road miles a year road so the chain stays much cleaner than those of you who ride on dirt or clean your friends chains. I also ride year round and get about two season before I need to replace the brushes.
The parts are used as replacements in the Park RBS-5 chain cleaning system. After cleaning many chains, especially wider ones, the bushes sort of wear out, which leads to reduced cleaning of the chain when used. By replacing the moving parts, the tool become fully functional again. Replacing the brushes is very easy and takes less than a minute. If you have the Park RBS-5 tool, check the inner brushes on the large rotating cylinder. These are the ones that wear the fastest.
If you are detailed about keeping your chain clean or your friends like to borrow your Park chain cleaner, then you will want this replacement Brush and sponge set. Brushes wear out and this will make your chain cleaner like new again.
These make the Cyclone more durable and justify the initial outlay, but if you don't have a Cyclone Chain Scubber, they would be pretty rubbish, so I wouldn't recommend them then.
I was not aware that replacement parts existed for the Park Tool Cyclone Chain Cleaner until I saw it on this site. The RBS-5 Replacement Brush Set gives new life to the best chain cleaner out there making it a great value. Keeping a clean chain helps save wear and tear on the cassette so it's a double great value!! Park Tool always delivers and they sure did this time!
I keep my chain very clean since it improves shifting performance on my ultegra equipped bike. I had worn out the innards on my Cyclone Chain Scrubber and this replcement kit was alot cheaper than buying a new one. The replacement parts fit well and have worked well so far although one of the brushes lost a few bristles at first. Good buy.