Make cold brew coffee at home the eco-friendly way! CoffeeSock ColdBrew filters are durable and may last a year or more. CoffeeSock ColdBrew filters are a reusable alternative to paper filters and nylon sacks. Cotton absorbs some of the oils released from coffee beans yet lets acids pass through. The resulting cup is clear crisp, rich, and robust with all the acid of paper brewed coffee, without the paper taste, and all of the richness of French press without the heavy oiliness. CoffeeSock filters are made with Certified Organic Cotton. Cotton imparts no flavor on the finished brew, unlike paper. Cotton is 90% cellulose, which is a tasteless and odorless compound that is insoluble in water.