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 prevent leakage. No primer required; can be installed and used after replacement, reducing initial flushing time. No low flow issues. Durable Lifespan: To maintain optimal performance, replace the filter every 6,000 gallons (depending on water quality). For proper siphoning in the drip system, fully submerge the carbon filter once a week. Note: Before installation, soak and flush the filter to remove residual manufacturing dust. Color: Black Material: Coconut shell activated carbon Package Contents: 4 x Water purification filter elements Note: Light reflection and different displays may cause slight color variations between the image and actual item. Measurement may vary by +/- 1-3 cm.