This product is a set of 4 water filter replacement cartridges designed for Berkey BB9-2 Black Filters and PF-2 Filters. These filters are compatible with Berkey and Waterdrop systems, and are made of coconut activated carbon block material for effective filtration. The filters are black in color, have a height of 10 inches, and a depth of 6 inches, providing clean and safe water for household, commercial, and off-grid use. They are specifically designed to remove fluoride contaminants, making them a reliable choice for water purification needs.