Used to have several discussions here about them but the only one that remains and hasn't fallen off the server is linked below.

Since that discussion 2 years ago I have bought another dozen but I continue to only use them on high acid foods and in BWB only. They work fine IME and many of mine have now been used multiple times. The only problem with them I have found is you have to very carefully remove then when opening the jar to avoid damage and wash both the rubber rings and the caps by hand - they melt in the dishwasher. (don't ask me how I know)

Dave

Here is a link that might be useful: Tattler Csnning Lids discussion