We kept one of those big, sturdy, heavy plastic coolers in the trunk of our car for things that need to be kept cold after grocery shopping, but we've substituted these new boxes. The main reason is that they fold flat when not in use, taking up much, much less space in our small car trunk.So how do they work? Mostly pretty well. They hold enough stuff but being made of heavy cardboard, you have to watch the weight. One gallon of milk would be fine, two would be maybe pushing it. But things likeSee full review