I was blown away by this thermos. Filled morning at 6:00 before a car trip, used to heat the bottle if need a bottle in the car, I emptied the thermos evening at 19h, and although the water was still warm ... amazing j 'yet have a thermos for coffee, but him not even four hours coffee remains cold, so I recommend this thermos bottle warmer. However, attention to closing opening pushbutton for not having paid attention I got burned but this result just my stupidity ... otherwise great product.