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 element uses high-quality coconut shell activated carbon as the filter material, providing a filtration precision up to 1 micrometre. Effectively removes impurities such as sand, rust, sediment, and odor, while reducing chlorine with a removal 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 prevent leakage. No priming 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 proper function, fully submerge the carbon filter in water once a week to support siphoning in the drip system. 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 differences in display screens may cause slight variations in color compared to the actual product. Measurement may vary by +/- 1-3 cm.