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. The latex nipple is made from a soft, brown material that is softer than silicone. The NaturaLatch nipple has been clinically shown to be similar to the breast. The slow flow rate is appropriate for babies 0-6 months.