I have come to understand that zip lock bags prevent oxidation of coins. The listed 2x2 bag does not give exact dimensions. Let me ask, will a 2x2 flip fit into it well or only a 2x2 cardboard flip??
These bags will work with the Guardhouse brand although it is an admittedly snug fit. Cowens is even tighter yet because of their thicker cardboard frame and I think you might find it frustrating to use this bag with them. That probably depends on your level of patience.