I wanted a bottle warmer that I did not need to connect even by car (there are many styles to connect with cigarette lighter) and do not put 20 minutes to heat up as some. I am delighted with my purchase, it takes about 2min30 to heat 180 ml. it allows me to go anywhere, even at the approach of the bottle time because I will not need to be near an outlet when the time comes. For a second bottle it will provide a longer heating time for a bottle still a little less hot, but it's still okay. It takes up space and weighs a little, but that's nothing compared to all the benefits!
