KOMFORTER is a patented design nipple made of Liquid Silicone Rubber (LSR Germany), Regulated anti-colic device - lets air into the bottles as baby sucks. This stops the nipple from collapsing, enabling the baby to get a steady stream without gulping air. Dots features provide similar comfort and structure of mother's nipple. All nipples can be reversed for comprehensive cleaning and can fit nicely into any standard feeding bottles. Sterilize before and after each use.