Uniquely designed to reduce colic. Comfortable feeding: Angled position promotes semi-upright feeding which is recommended by pediatricians to help prevent ear infections. Leak-proof: New Twist 'n Click seal helps prevent leakage - just twist the nipple ring on tightly until you feel the click and the arrows on the bottle and nipple ring are aligned. Versatility: All Playtex nurser nipple rings and caps are interchangeable with Playtex VentAire wide reusable bottles for greater flexibility. Playtex selected the NaturaLatch nipple for all 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. Drop-Ins liner: As the baby feeds you can see the soft liner gently collapsing to prevent air from mixing with the milk and getting into baby's tummy. This means less gas and less discomfort for baby. The convenient Drop-Ins disposable liners are: pre-sterilized for a clean bottle anytime and anywhere; pre-formed for easy, one handed assembly and clean-up. 3 months+. BPA free. Contains: 1 8-10 oz (236-300 mL) bottle with NaturaLatch silicone nipples, 5 pre-sterilized Drop-Ins liners.