This product uses nanotechnology (which is the science and technology of building devices, such as electronic circuits, from single atoms and molecules) to help keep foods fresh. The short answer is, it inhibits mold & germ growth, Different sizes for any use, Air-tight storage, Freezer, microwave and dishwasher safe. BPA Free Always Fresh Containers help to extend the life of fruits, vegetables, cheese, bread, meats. During the ripening process damaging gases are released. Exposure to these gases speeds up the aging process, Always Fresh Container are made with special material that absorbs and removes these damaging gases, extending the life of foods.These environmental friendly reusable containers also help reduce vitamin loss without the use of harmful chemicals and keep all foods fresh longer. 20 pc. set. Nested so it stores easily!