Reusable, eco-friendly linen coffee filter. Simply made from 100% linen fabric. It extracts the coffee's oils, which are absorbed by paper filters. Wet it before use to help it fit the dripper. You can enjoy both a light taste and a rich, deep flavor depending on the drip speed. After use, wash gently with water or hot water and hang to dry. If you're concerned about oil, wash with soap. Please understand that this is handmade by an amateur. By the way, I've been using it about twice a day for several months, and it still seems to be usable. Each side is 13cm long. It can be used for a 4-5 cup dripper.