The Evenflo Feeding Classic Standard Neck Nipple is 100% silicone and features micro air vents to help prevent nipple collapse. The nipple has a gradual transition between nipple length and base to allow your baby to maintain their latch. The Classic Nipple can be easily assembled and disassembled from an Evenflo Feeding Classic Bottle, for a quick, thorough cleaning between feedings. The dishwasher safe nipple (top rack only) is available in three flows: Slow, Medium, and Fast. The nipple is 100% free of BPA, polycarbonates, PVC and phthalates, and is also made of FDA-approved food grade material.