The Adiri NxGen Nurser was designed with the logic of a baby bottle having pure flow, ease of operation and cleaning, and to support breast to bottle transition. Its bottom vented one-way Petal valve offers consistent air flow reducing the possibility of colic. </br>Features: </br>Bottom vented, one-way petal valve offers consistent air flow reducing possibility of colic. Supports transition from mother's breast to bottle. Soft medical grade silicone nipple that is ideal in shape and size. Bottle disassembles in 3 convenient pieces for ease of cleaning. BPA free.