Replacement O-rings and Valve Membranes for the Medela Harmony pump are designed by Maymom to help maintain optimal performance and suction. This set includes 4 O-rings and 2 silicone membranes, providing the essential replacement parts needed to keep your pump functioning smoothly. Made from BPA-free and DEHP-free materials, these components are safe, durable, and easy to install for convenient maintenance and continued reliable use.