How to identify O2 absorbing caps

[slt140]

I am somewhat new to this (10 extract batches) and have a question about O2 absorbing caps. The caps I use either come with the kit I bought or were aquired from my local homebrew shop. They do have a plastic/rubber coating on the inside, but how do I know if it is the special kind or not? The reason I ask is I am debating sanitizing them or not due to the belief that sanitation of the caps renders the "absorbing" qualities of the cap ineffective.
Thanks folks.

 

[ChshreCat]

From what I've heard (which is far from definitive, of course) is that while they're activated when wet, they absorbe O2 for quite some time after that. So, I usually take them out of the bag a dozen or so at a time and spray them with my starsan bottle and then use them.

All my O2 absorbing caps have something on them around the edge of the crown identifying them as O2 absorbers.