Ancient coins in general don't need to be protected. You're meant to touch them.
Every storage system that makes it harder for you to look at and touch your coins is very bad.
I used these folders for a while, with plastic
flips in them. These weren't sealed but getting at the coins was
such a bother that I hardly handled them.
Now I use trays, I can easily touch my coins, turn them over, resort them if I like and it's much better.
Coins that you can't
handle are useless and for that reason
collections of modern coins that you can't touch
are stupid. Yes I said it, so sue me.
There are a few exceptions, e.g. coins with very fragile patinas but I avoid these.
I
had one that was beautiful and not common but If I'd dropped it on my desk I know parts would have come off, so I sold it.
I never would have done so otherwise.