Product Features: Clinically proven to reduce nipple preference in established breastfed babies Encourages natural oral development Enables baby to use feeding actions learned at the breast Air Ventilation System (AVS ) reduces intake of gas, a potential cause of colic or spit up Fewer parts - easy to assemble & clean NaturalWave Nipple is 100% silicone, soft, flexible and designed for optimal compression The Lansinoh mOmma Bottle with NaturalWave Nipple is clinically proven to reduce nipple confusion in established, breastfed babies. Backed by more than 50 years of research, the silicone NaturalWave Nipple enables baby to engage in the natural, wavelike sucking actions learned at the breast, making it easier for baby to go from breast to bottle and back to breast. The Lansinoh mOmma Bottle is BPA and BPS free and can be used to safely store breastmilk in refrigerator or freezer.