When you are out and about don't forget to take along the Baby Bottle Warmer Portable from Our Precious Kids .If you were unplugged, it will keep the contents of a bottle warm for about 2 hours. Unless you are heating it up continually! Our Warmer will continually keep the milk or contents warm. It also sterilizes the milk to keep your baby safe! Additional Features Keep warm temperature stay at 40, don't worry about the milk overheating. Very compact to carry, You could put it in your diaper bag, or hook it on the stroller. Insert the cable into the mobile power supply, or the vehicle USB interface, the notebook computer interface. (this product does not contain portable batteries) Fits most bottles, please check the size with your bottle.