No insulation at all.

This vacuum bottle does a great job of keeping my hot tea hot for most of the day. It seals tightly, and allows for pouring with the push of a button, which is very convenient. It also is slim enough to fit into the cup holder in my (older) car, which is a really positive asset to me. And it fits well into my tote bag, so I can always have my hot drink accessible. I would highly recommend it.

Worth the money! The product was in very good condition when I received. It keeps the fluids warm upto 8 hours. I recommend this product to everyone looking for a good stainless steel flask.

I drink/sip hot water and ginger tea all day long at work and at home, and I find this thermos works very well for my purpose. Besides the obvious point that the product is all stainless steel and therefore safe and healthy, what I REALLY like is the fact that the beverage stays hot for a long time, even with the cap off. In the morning I put in a small spoonful of dried chopped organic ginger and fill the thermos with very hot/ sometimes boiling water (but boiling is not necessary). I drive to work and this bottle fits nicely in the car cup holder. It's easy to take a sip as I am driving. At work I keep the thermos at my desk and sip all day long. When the tea gets low I just add more hot water from the spring water dispenser. This is much healthier than drinking coffee all day long (although I do drink coffee every day!). This particular set of two is a fantastic deal. Previously I used a true Thermos brand thermos that looked pretty much the same as this thermos and I loved using it for the same purpose. Unfortunately, I threw it away by mistake and needed a replacement. Bummer! But, the good news is these two stainless steel bottles work great and the price is so reasonable! You can't go wrong with this purchase.

UPDATE: As others have noted, this bottle leaks. If I was traveling I would buy the actual Thermos brand bottle as that one never leaks. These bottles still work very well for the uses I described above. The problem is the cap and gasket, not the bottle itself. The bottle is very good quality.

Great inexpensive flasks.. My wife and use them for short vacations to store our cocktails while we are in the hotel rooms. They work fine, do not leak and all pieces can be washed in the dishwasher.. We had other similarly made ones and they lasted us 10+ years.... I expect these to do as well...