I realize that Larry that's why I qualified my statement. Yours could definitely be better than what I was getting originally. They weren't lasting so I needed something better. The a/c orings were a fluke. I had them for a/c work and one was an exact match so I tried it. I completely forgot it was in there until another original oring failed. Everything has them now. They rarely fail from tearing but they do eventually dry out and shrink but it takes a long time. I came to the conclusion that they have to be consistent because the industry requires it. On the other side we have no such requirement and if it fits it will work at least for a while. Who makes sure they are being made correctly

Nobody

Remember the Chinese drywall.
Dan, I don't doubt your info except they are for a/c systems which are cold by nature and in cars all over the U.S. Direct exposure may cause a problem that the sealed a/c system solves. I'll stick with them until I find something better. It's always hot here even during our supposed winter. Cold will never be an issue. I have some buna nitrile but none of those fit so I couldn't test them.
Gene