To avoid feeding your baby with too hot a bottle, NUK First Choice + * bottles now include the new NUK temperature control. It looks like a thermometer, it is located inside the graduation marks and the temperature of the contents of the bottle makes the indicator change color. For example, if the milk is very hot, the indicator, which is usually blue, will change to white. Ideally, baby food should be at body temperature (37 ° C = medium blue tone). Please check the temperature again before giving the bottle.