This food container is amazing! Following the instructions, I put boiling water in it first thing in the morning while getting ready. Then I cook my son's spaghetti o's or whatever he's having for lunch, get it piping hot, dump the boiling water and immediately replace with lunch and seal it up. This container goes inside a frozen lunch bag, like PackIt, along with his water, applesauce, etc. At lunch time, after being in a frozen bag all morning, it is STILL HOT. And it does not heat up the water or applesauce that it was packed with. Everything else stays cold. To me, it's just amazing insulation. I considered the 10 oz., but my son is 14 and can easily eat a whole can of soup, pasta, stew, all those things that come in a 15 oz. can, and they fit perfectly in this jar. He's been using it 5 years regularly and still works perfectly.