Zojirushi Mr. Bento stainless lunch jar comes with 4 microwaveable plastic inner bowls that fit inside a stainless-steel vacuum insulated outer container. The inner containers allow you to compartmentalize your food and bring an entire meal, like a pasta dish, soup, salad, and cookies in each separate bowl. The main and soup bowls stay hot or cold, and the two side bowls stay at room temperature, divided from the main bowl by an insulating inner lid. All lunch jars feature Zojirushi's high-tech vacuum insulation provides superior heat retention to keep contents hot or cold for hours. Inner bowls are microwaveable (except inner lids) so meals can be packed the night before, and then quickly reheated the next morning. A silicone gasket and tight-fitting lid on the soup bowl help to minimize leaks. The pressure release valve can be utilized to release built-up pressure if the soup bowl lid becomes difficult to open. The outer container has a nonstick coated interior and is washable (do not soak in water). Also includes a forked spoon with cover and easy to carry bag.