All Playtex Drop-Ins System bottles come with a Playtex NaturaLatch nipple that encourages proper latch on for baby to prevent her from taking in air. It has a wide base and a raised, textured area that helps encourage switching between breast and bottle. This medical grade silicone nipple holds its shape and can be repeatedly sterilized. The NaturaLatch nipple has been clinically shown to be similar to the breast. The Fast Flow rate is appropriate for babies 6+ months.