Evenflo"s classic glass bottles let you easily monitor your baby"s intake of milk or formula. They are 100% recyclable and BPA free. The CustomFlow nipples sense Babys pressure and respond with the right amount of liquid. Micro Air Vents promote an even flow of liquid and help prevent nipple collapse. The bottles hex shape is easy for Mom and Baby to hold, and each bottle includes a matching hood for easy storage and transport.