This product is designed to use with these pumps: Spectra S1, S2, Spectra 9 Plus, Spectra Dew 350 breastpumps, and All Medela breastpumps, except Medela Freestyle. It also works with Nenesupply breastshields. One duckbill valve replaces Medela valve and membrane. No need to buy extra membranes. With this newly designed valve, breastfeeding moms have fewer pump parts to wash, sterilise, and assemble. Medela membrane is thin and small, and can get lost easily. Made from BPA free materials, and complies with EU regulations for materials that contact food. The material is silicon, the same as Medela membrane and Spectra valve. They are safe to sterilise in water steam or boiling water.