Medela authentic spare valves and membranes are engineered, tested, and approved for use specifically with your Medela breast pump – Spare parts that are not authentic can vary significantly in terms of design, materials used, and overall workmanship, all of which may affect the performance of your breast pump. Compatible with Pump in Style, Swing, Sonata, and Symphony breast pumps and Medela PersonalFit breast shields. Not compatible with Pump in Style with MaxFlow, Swing Maxi Hands-Free, Freestyle Hands-Free, and Pump In Style Hands-Free breast pumps. What’s Included: (2) Valves; (2) MembranesAs always, all Medela breast pump parts and accessories that come into contact with breast milk are made without BPA.