Uniquely designed for strength, these gourmet filters are made of high-quality, heavyweight paper so the water flows properly through coffee grounds. Sides are taller, & you don't end up with overflow & grounds in your coffee. Paper stock used in the manufacturing of these coffee filters is produced using an elemental chlorine-free (ECF) bleaching method. This process insures that there will be no detectable level of dioxin in these paper coffee filters.