[Filtration precision up to 1 Micrometre]: This filter element uses high-quality coconut shell activated carbon as the filter material, providing filtration precision up to 1 micrometre. It efficiently removes various impurities such as sand, rust, sediment, and odors, while effectively reducing chlorine with a removal rate of more than 99%. [Compatible Models]: Compatible with Berkey gravity filtration systems including Travel, Grand, Royal, Imperial, and Crown Series. Replaces BB9-2 water filter elements. The precision design of washers and wing nuts ensures a secure connection and prevents leakage. No primer required; can be installed and used after replacement without 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 ensure proper siphoning in drip systems. [Af able and cost-effective]: This filter delivers comparable filtration performance to name-brand equivalents at a more af able cost, offering high-quality water filtration with cost efficiency. [Note]: Before installation, soak and rinse the filter thoroughly to remove residual manufacturing dust. Color: Black. Material: Coconut shell activated carbon. Package Contents: 4 x Water purification filter elements. Only the above items are included; other products are not included. Note: Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement error is +/- 1-3 cm.