I would like to warn all cosumers about Tupperware's Modular Mates Cereal Keeper Lids. They DO NOT seal at all.
They allow ants to get into the container. You cannot replace them, so my advice, do not buy them at all. Or, if you buy that size, ask for a solid lid, not the kind with the tiny thin flap.
I love Tupperware products, but now I have to go out and try to find all solid lids for my cereal keepers! Tupperware would do well to help consumers who are not satisfied with the quality of their product to replace something that does not keep food fresh or bugs out!