Four used non-woven fabric filters for Free Science Soryusui One Water ECO. Each filter was used for approximately 3 months, then washed with Soryusui water, air-dried, and stored at home. Some filters have yellowing and blackening. (The degree of staining varies due to moving.) Please check the photos and purchase only if you understand. I will take measures to prevent water damage and package the items. Please purchase only if you understand that these are items stored by a private individual. Please refrain from purchasing if you are looking for perfection or are overly concerned about details.