The Evenflo 4 Oz Tinted BPA Free Bottles do not contain bisphenol-A (BPA). Contains polypropylene, which is 100% recyclable which is important to eco-conscious Moms! The Sensitive ResponseTM nipple senses baby's pressure and responds with the right amount of liquid and the Micro Air VentsTM promote an even flow of liquid and help prevent nipple collaspe. Also features hex shape for an easy grip