Missing or worn out membranes and valves will negatively impact your pump's suction. Evenflo Feeding’s Replacement Membranes and Valves include 2 Bpa-free silicone membranes and 2 Bpa-free valves. The membranes are tinted silicone, making them easier to find during assembly and cleaning. The extra membranes and valves work with all Evenflo breast pumps, including our Advanced Double Electric, Single Electric, and Manual pumps. Help maintain optimal performance of your breast pump and keep a pack of replacement membranes and valves on hand so that you always have a perfect pumping experience!