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 more than 99%. Compatible Models: Compatible with gravity-fed water filtration systems including Travel, Grand, Royal, Imperial, and Crown Series. Precision-designed washers and wing nuts ensure a secure connection and help prevent leakage. No primer required; filters can be installed and used after replacement, reducing initial flushing time. Durable Lifespan: To maintain optimal performance, replace the filter every 6,000 gallons (varies based on water quality). For proper siphoning in drip systems, fully submerge the carbon filter at least once a week. Note: Before installation, soak and flush the filter thoroughly to remove residual manufacturing dust. Color: Black Material: Coconut shell activated carbon Package Contents: 4 x Water purification filter elements Note: Light reflection and differences in display screens may cause slight variations in color compared to the actual product. Measurement may vary by +/- 1-3 cm.