|Bottom vent: Unlike ordinary bottles that vent through the nipple, the VentAire micro-channel vents keep air at the back of the bottle as baby drinks, so virtually no air mixes with the milk and gets into baby’s tummy. Angled bottle: Angled design promotes semi-upright feeding position recommended by pediatricians to help prevent ear infections. Versatility: All nipple rings and caps are interchangeable with Playtex nurser bottles for great flexibility. Playtex selected the NaturaLatch nipple for all of our bottles because it mimics baby’s latch-on like the breast. The natural nipple shape has a raised texture area that helps baby latch on naturally. Leak-proof Uniquely designed to reduce colic Helps reduce air ingestion BPA free.