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 precision up to 1 micrometre. It efficiently removes impurities such as sand, rust, sediment, and odor, while effectively reducing chlorine with a removal rate of more than 99%. Compatible Models: Designed to replace BB9-2 filters. Compatible with gravity-fed water filter systems including Travel, Grand, Royal, Imperial, and Crown Series. Precision-designed washers and wing nuts ensure a secure connection 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 function, fully submerge the carbon filter in water once a week to support proper 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 different display settings may cause slight color variations between the product image and the actual item. Measurement may vary by +/- 1-3 cm.