Paper filters feature high-quality construction that is a vital step in brewing perfect coffee in your 6-gallon (22.7 liter) urns that use 21" diameter filters with 8-3/4" diameter bases. Using the results from years of research, BUNN manufactures the filters from high-quality, specially manufactured paper so the water flows properly through the coffee. BUNN filters are uniquely designed for strength with taller sides to reduce overflow and grounds in your coffee. Its paper stock used in the manufacturing of the coffee filters is produced using an elemental chlorine-free (ECF) bleaching method. This process ensures no detectable level of dioxin in these paper coffee filters. BUNN's paper stock supplier conducts regular testing, as required by the Environmental Protection Agency (EPA), to confirm that no detectable dioxin is present.