Instruction: Given a question and the related document, and generate the answer to the question based on the information provided in the document.

Input:
Question: Is the interior plastic or stainless steel
Document: It makes it much easier to get food like fried rice into the food jars. I found it to be very useful. Amazon sells really nice stainless steel canning funnels. Search for the term to see what it looks like. The giant W has a cheap plastic one (that happens to be Made in USA).
Bought this to replace a plastic glass lined thermos bottle I had before for hot foods. The old plastic bottle never really kept the food that hot. The Stanley bottle really works nicely. Food stays hot for hours(you have to preheat the bottle with hot water first). Easy to clean and completely un- breakable, being that it is all stainless steel.
Just what I needed at a perfect price! I love the big stainless steel water thermos as well. Priceless! Yeah
To make matters worse, they sound like a cheap stainless steel sink. At best I was able to keep food hot for 4-5 hours in a primed bottle.
NEVER. I keep using it solely because the stainless steel doesn't absorb odors and as long as I don't mind lukewarm curries it's the best method I have of carrying it for lunch.ETA: Stanley replaced my thermos and the new one works as intended. My lunch is warm and I'm happy with the purchase. Perhaps the one I originally had was somehow defective or damaged during shipping.
This jar was another step on my path to take my lunch without plastic bags or containers. It's a great size and keeps things hot or cold just fine -- and the color reminds me I'm "going green."
Keeps my beverages and soups warm for a very long time. I love the sturdiness and weight of it. One note: make sure you don't discard the rubber/plastic ring that sits around the screw-in cap. It will leak without it.
Also there is a white plastic gasket between the bottle and the lid. Often the gasket will fall out when the lid is screwed on. There is no way to check, but when it falls out into the liquid inside, the food loses heat fairly rapidly. I can get much less expensive vacuum bottles that will break just like this one so why should I pay more?
I use these Stanley Steel classic food jars mainly for soups and stews to take to work. Put it is piping it hot right off the stove and it STAYS piping hot for HOURS! And DURABLE doesn't even describe it. I have a couple that I have owned for several years and are banged up a bit from various drops but they still work well. I recommend this product highly.
I really like this thermos. I bring soup to work and it stays piping hot. I hand wash it, and put hot water in it before I put my soup in. I have also used it for coffee, spaghetti, and other casseroles and they all stay hot for me. I did drop it without the top part screwed on and the plastic piece that you first screw on broke and I needed to get a new one.
Answer: The interior is stainless steel. The only part of the thermos that is all plastic is the twist on  inner cap. The outer cap has plastic on the inside of it, but the outer part is stainless steel.