Wears out or stretches so that it needs to be replaced. I thought Kohler was the best. Not any more!

At first I used an O-ring from the hardware store. It didn't last.

This is the O-Ring for a Kohler kitchen sink basket strainer (K-8801-CP). I think it's the nicest strainer on the market, but the O-rings do not last. They expand, fall out of the groove, and need to be replaced. I order 8 - 10 at a time. I have stopped pouring boiling hot water into the sink, as this may have been the cause. O-rings work fine when they are new. Thank you.

These o rings are made from cheap material. After a few weeks of being exposed to sink water, they expand and will not stay on the sink strainer. I have to keep at least 20 of them on hand at all times. If this is indicative of kohler quality, then I want no more of it. Will buy a different brand sink strainer next time.

Have had this less than a month and the o-ring in the gooseneck has come out twice. It's very small but we found it the first time. This time we can't find it so no faucet or water again.