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: 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; can be installed and used after replacement, reducing initial flushing time. No low water flow issues. Durable lifespan: To maintain optimal performance, replace the filter every 6,000 gallons (depending on water quality). For proper function, fully submerge the carbon filter in water once a week to maintain the siphoning action of the drip system. Note: Before installation, soak and flush 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 differences in display screens may cause slight variations between the color of the item in the image and the actual product. Measurement may vary by +/- 1-3 cm.