4PCS Water Filter Replacement for BERKEY Black Activated Carbon BB9-2 Filters for Gravity-Fed Water Filter System Filtration precision up to 1 Micrometre: Designed for excellent filtration performance, this filter uses high-quality coconut shell activated carbon as the filter material, with a filtration precision up to 1 micrometre. Efficiently removes impurities such as sand, rust, sediment, and odor, while effectively reducing chlorine with a removal rate of over 99%. Compatible Models: This filter is compatible with gravity-fed water filtration systems including Travel, Grand, Royal, Imperial, and Crown Series. The precision design of washers and wing nuts ensures a secure connection and helps prevent leakage. No primer required; the filter can be installed and used directly after replacement, reducing initial flushing time. Durable Lifespan: To maintain optimal performance, replace the filter every 6,000 gallons (subject to water quality). For proper siphoning in the drip system, fully submerge the carbon filter in water once per week. Note: Before installation, soak and rinse the filter thoroughly to remove any residual manufacturing dust. Color: Black Material: Coconut shell activated carbon Package Contents: 4 x Water purification filter elements Note: Light reflection and different display settings may cause slight color variations between the product image and the actual item. Measurement may vary by +/- 1-3 cm.