Feeding made easy with NUK First Choice+ Temperature Control Bottles. The NUK orthodontic-shaped teat is modeled on a mother's nipple as she breastfeeds and is particularly well accepted by babies that are bottle and breastfed. Babies can enjoy a natural flow without swallowing air thanks to the NUK Anti-Colic Air System and parents can enjoy the extra reassurance that the milk is at the right temperature thanks to the NUK Temperature Control indicator.It is located within the graduation marks of the bottle and changes colour if the milk is too hot. If milk is too hot, the normally blue indicator will turn white.