This is a replacement valve for Medela breast pumps. According to the Medela breast pump instructions, this corresponds to the "white membrane" and the "breast milk valve (pale yellow part)". - Brand: nenesupply - Compatible models: medela Swing electric breast pump / Harmony manual breast pump Essentials Pack / Harmony manual breast pump / Symphony electric breast pump ◎ Contents Breast milk valve kit ◎ Washing instructions When washing, gently hand wash without using a brush. Sterilize in the microwave, steam, or by boiling. The white membrane should be replaced every month (the degree of wear and tear varies depending on frequency of use and sterilization method). Heat resistance: 160°C. Note: Be sure to clean and sterilize before use. ◎ Materials Polypropylene, silicone. Manufacturer: Nenesupply Co., Ltd. Importer: Roaming Saver LLC Thank you for viewing. This is a replacement valve for Medela breast pumps, made by the manufacturer nenesupply. I purchased it online. There were 8 white membranes, but I used one, so there are 7 remaining. There are 4 unused pale yellow breast milk valves, as they were when purchased. The compatible breast pumps are as listed above (photo 2). Thank you for your consideration.