The shape of the Closer to nature fast flow teat is similar to a real nipple. They enable baby to experience the feel of natural nursing. Helps baby alternate between nursing & bottle feeding. Ultra-sensitive anti-colic valve to prevent baby swallowing air that may cause discomfort & colic. Can be sterilised in hot or cold water. In silicone. Suitable from 6 months. Closer to nature teats for babies aged 3 to 6 months also available on this site. Please note: this is a green star item no extra discounts apply.