The Berkey BB9-2 Water Filters Replacement Purification Elements are a 2-pack of high-quality water filters designed for commercial and household use. Made with stainless steel, ceramic, and steel materials, these filters use carbon/charcoal filtration method to remove contaminants such as fluoride. With a capacity of 2 liters each, these black filters are compatible with Aqua Optima and FilterLogic brands, specifically designed for Aqua Optima Evolve models. Made in the United States, these Berkey filters are a reliable and efficient solution for clean and safe drinking water.