4PCS Water Filter Replacement for BERKEY Black Activated Carbon BB9-2 Filters for Gravity-Fed Water Filter System Filtration precision up to 1 micrometre: This filter uses high-quality coconut shell activated carbon as the filter material, providing filtration down to 1 micrometre. Effectively reduces impurities such as sand, rust, sediment, and odor, while absorbing residual chlorine with a reduction rate of over 99%. Compatible models: Designed to replace filters for gravity-fed water filtration systems including Travel, Grand, Royal, Imperial, and Crown Series. Precision-designed washers and wing nuts ensure a secure fit and help prevent leaks. No primer required; ready to use after installation with minimal initial flushing. Durable lifespan: For optimal performance, replace the filter every 6,000 gallons, depending on water quality. To maintain function, fully submerge the carbon filter in water once per week to support proper siphoning in the drip system. Note: Before installation, soak and rinse the filter thoroughly to remove fine particles from manufacturing. Color: Black Material: Coconut shell activated carbon Package contents: 4 x Water purification filter elements Note: Light reflection and display settings may cause slight variations between the color in the image and the actual product. Measurement may vary by +/- 1-3 cm.