Nothing to say. This is a seal. My original lasted over 5 years. I'm only replacing it now because I can see some small cracks in it and it might last a while longer but I don't risk it leaking. I will buy a backup for my 305 and 405 as soon as I can. This may sound silly, but when I was an assistant plumber, he taught me a trick when it comes to anything with O-rings. He kept the tuner KI Kelly in his box of O-rings and lubricated them before repairing faucet valves or other rubber parts. And KY is harmless and not harmful if it gets into the water or is in our aquarium now. I'm not sure if all types are available, you just need the original KY.
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