Dr. Brown's narrow-neck "Options" teat promotes a natural latch-on, and more closely resembles the breast making it easy to combine breast and bottle feeding. The anti-colic system reduces discomfort by venting air into the bottle and not your baby's tummy. This Level 4 fast flow teat is great for older babies who are pros at bottle feeding. The suggested age range is 9 months+ but baby’s preferred flow rate may vary. This set contains 2 pieces of the same soft silicone teat that is BPA free.