There may be things that work perfectly, but I don't use them...

Some people use airtites...but I like 'em in the binders for easy access and viewing

Some people use paper coin envelopes...again, I like to be able see 'em without removing them from their holders

Some people use the flips, but the non-vinyl ones seem brittle to me, and I don't like to handle 'em

So I use the cardboard/mylar holders in the plastic pages, and haven't had too many major problems.