These are assembled together to product the valve for your breast pump and are compatible with all Spectra breast pumps. You can use these interchangeably with the Spectra duck valves, depending on which type of valve you prefer.
Each membrane will last around 2-3 months (less if exclusively expressing), and are an item that requires replacement over time. If you notice that your breast pump seems to have less suction or you are expressing less milk, the membranes should be the first thing you check.
Packing : Valve head x 2pcs, Membrane x 2pcs / Pack