This 4-pack of high-performance replacement filters is designed for gravity-fed water filtration systems. Each filter is constructed from premium coconut shell activated carbon, providing filtration down to 1 micron. They effectively reduce sediment, rust, sand, chlorine (over 99%), and unpleasant tastes and odors from your water. These filters are compatible with various gravity system models, including Berkey's Travel, Grand, Royal, Imperial, and Crown series. The precise design of the included washers and wing nuts ensures a tight, leak-proof seal. Installation is straightforward with no priming required—simply replace and use, saving time and water. For optimal performance and system longevity, it is recommended to replace filters every 6,000 gallons (actual lifespan may vary based on water quality). To maintain proper siphon flow in drip systems, fully submerge the carbon filter in water once a week. Before first use, soak and rinse the filter to remove any fine carbon dust from the manufacturing process. Color: Black Material: Coconut Shell Activated Carbon Package Includes: 4 x Water Purification Filter Elements Please note: Product color may appear slightly different due to monitor settings and lighting. Slight dimensional variations of +/- 1-3 cm are within manufacturing tolerances.