These lids are helping me reduce the amount of cling wrap and foil that I use when storing leftovers. They aren't a cure-all, at least for me. As many others have noted, it takes some practice and skill to stretch them over container openings, and if there is the slightest moisture or oiliness on the outside of the container, the attempt will be fruitless. Over the period of a few months, I've become more successful. I have even managed to use them on small plates (leftover tortillas), which hav...