For safety and hygiene purposes it is recommended that you replace teats after 1-2 months of use or whenever they start to show signs of wear. Prior to sterilisation it is recommended to use the NUK Baby Bottle Cleanser, its natural formula removes dried on milk protein, pulp and juice residues more effectively than hot soapy water alone. To sterilise bottles and teats use steam, cold water sterilisation or a NUK Steam or Microwave Steriliser. Dishwasher sterilisation not recommended as this can cause material damage. Please note, NUK Nature Sense teats can only be used with NUK Nature Sense bottles, they do not fit other types of NUK bottles.