Cardboard Coin Holder Questions?

May I add that it is possible the coin can slide out of these flips if misused , where as the cardboard 2x2 the coin isn't going anywhere .

Cowens, Heco, Whitman and the Generic all pretty good, I use them all along with a flat cinch stapler and a pair of needle nose pliers to crimp the staples extra flat, then I use double row 14" cardboard boxes, some older Whitman blue plastic boxes, and a few single row cardboard boxes which are then stored in either Tupperware bins or a pelican case. Along with some de-humidifier material. Food safe plastic bins should always be safe to store coins in without worrying about outgassing or PVC it's not used in food safe containers, at least it's not supposed to be. I'm in a fairly humid area now, so I always use the de-humidifiers or desiccant packs and recharge them or replace them pretty regularly. Heat, UV light and humidity are your worst enemies when it comes to copper and silver coinage.

The only ones I've had issues with consistently are the ones from Hobby Lobby, full of lots of cardboard dust and the pre-scored folds are not always straight or even. I will no longer get any from them, I used them in a pinch a few times since they have a store down the street from me.