Closer to Nature anti colic bottles provide optimum venting during feeding via a unique tube and valve system. Air can enter the bottle safely, vents down through the tube and into the air-space at the base of the bottle, completely bypassing the milknThe Anti colic nipple with wide neck design allows for an easy and more natural latch on for your baby, so there is less risk of air being taken in during the feeding process.nRevolutionary soft silicone nipple developed with breastfeeding experts and Moms, feels like skin and gently elongates and flexes during feeding to mimic a natural breastfeeding action. Closer to Nature Bottles makes feeding time easier for Mom and Baby.nThe compact shape of Closer to Nature bottles allows baby to feed in a natural position and to be closer to Mom or Dad.nFor total reassurance, all of our products are free from Bisphenol A (BPA).nThe Tommee Tippee Closer to Nature sensitive tummy bottle is designed for babies with excessive spit up, fussiness and gas. The super sensitive, unique tube and valve system provides optimum venting so baby takes in more milk or formula and less air. The soft, natural shaped nipple mimics the feel, flex and movement of breastfeeding, similar to mom's own natural feeding action providing a smooth transition between breast and bottle. All features combined provide baby the most natural alternative to breastfeeding and a comfortable, stress free feeding experience.