PopYum nipples are recommended for feeding newborns and older and are compatible with PopYum formula making baby bottles. PopYum's wide nipple design and natural latch support a smooth transition from breast to bottle. The anti-colic vent returns air to the bottle, not baby's tummy. Safe Materials: Created by concerned parents, the nipple is made of only medical grade silicone. We invite parents to compare our materials to those of any other nipple. PopYum is BPA, BPS, latex, lead, nitrosamines, PET, phthalates, PVC and TPE free.