A bento box is a lunch container that has multiple compartments for packaging food. These are usually made of stainless steel or plastic, which gives the containers their "bento" appearance. You may also see these boxes referred to as lunch kits, food carriers, and lunch pails, to name a few. A bento box can be used to pack both hot and cold foods (or simply snacks). The most common design includes three sections: The main container, lower compartment, and lid. A thermos bottle can also be used as a lower compartment, but you should not fill it with food as it will not be as effective at retaining heat. You may add another compartment if you want to pack cold or hot foods separately or separately in containers that are separate from your lunch box.