When it comes to storing leftovers, the truth is any used margarine or yogurt tub will do in a pinch. Just clean it out, load it up, and upcycle that non-descript plastic container with a clear conscience. But don’t put it in the microwave, or the freezer, or the dishwasher—unless you want a BPA-laden bowl to become part of your next meal. For maximum shelf life and utility, it’s best to keep a few purpose-built storage bins in rotation. They’re microwaveable, dishwasher-safe, and engineered to keep second helpings as fresh as the first. Here are a few things to consider before you buy more.