The unique valve on the nipple flexes to your baby's feeding rhythm. As your baby feeds the unique valve on the nipple opens to allow air into the bottle instead of your baby's tummy. Milk will only flow at the pace chosen by your baby to minimise overeating and spit-up burping and gas. Classic+ bottle is designed to prevent leakage whilst feeding for a truly enjoyable feeding experience. The bottle has only four parts for quick and simple assembly. With a wide bottle neck and rounded corners our bottle is also easy to clean quickly and thoroughly.