I have used these cubes for a few years now and love them! I send one out the door a few times each week with one or another daughter for the school lunch hour. I find ours at The Container Store. What I love about the lunch cube is that a full size sandwich fits on the bottom and then on top, chips, cut up fruit (or small fruit; one prob I have with the system is that an apple does not fit into the cube :)) or another smallish foods. These lunch cubes are BPA-free, made from polypropylene and have an airtight rubberized silicone seal that keeps your sandwich fresh :). Enjoy!
Find yours here: Container Store.