The Zoo Friends anatomic nipple from Evenflo is made from soft, flexible silicone. Designed for 8+ months, the anatomic nipple has a winged shape that fits the corners of Baby"s mouth, reducing air intake for less gas and fussiness. Micro air vents help prevent nipple collapse by balancing the air in the bottle. Designed for use with Zoo Friends bottles, these nipples also fit Evenflo classic bottles. This four-pack includes a special brush designed specifically to clean nipples.