I looked for date on my filters to just to see and relay on info.
I see only the number 71 and next to that I see 298
I am going to guess they are charcoal, how fast dose charcoal go bad, I think it lasts a long time when sealed. I would not even buy filters that did not have original seals fully intact. humidity and God knows what else could get in.
I am off the page for extended times due to job requirements, not gone forever