These colour changing discs are placed into baby's bottles when making up the feed. They float in the milk and turn from purple to pink at 37 and#778; C to show when milk is too hot to drink. Easily washed and sterilised in the bottles. Made from an amazing plastic which changes colour from purple to bright pink between34 and#778; C and 39 and#778; C. Below 34 and#778; C the indicator discs are purple, but above 39C, the discs are bright pink, giving a visual warning that the milk is too hot and must be cooled. Helps to prevent scolds This pack contains 6 colour changing bottle indicator discs and 1 food tester in a handy clip-close storage box Indicator discs give an easily visible indication when babys bottle milk is too hot.