Fluoride and Reduction - Fluoride and Reduction Elements Replacement Filters are designed for use with Black elements to adsorb fluoride, (V) and pre-oxidized (III) as well as other typical heavy metals Residual ions. Economical and Durable - Provides filtered water for just pennies per gallon. Each pair of Black Elements has a lifespan of up to 6,000 gallons and replacement is recommended. Depending on the quality of the incoming water, the filter may need to be replaced as soon as possible. We recommend replacing the fluoride reducing Elements after 1,000 gallons of normal use. [High Efficiency Filtration]-This water filtration Elements set is an alternative to gravity filtration system filters, has passed high standard testing by authoritative institutions, and effectively reduces chlorine, fluoride, heavy metals, taste and odor, sediment, particles and other harmful substance. Enjoy clean and healthy water outdoors at any time. [ Black Filter]- black filter is made of high-grade and high-quality materials. Compared with ordinary granular activated carbon, it has higher adsorption capacity, effectively reduces fluorine and chlorine, and filters impurities. Colour:white+black Material:plastic Package Contents: 4 x water filter 4 x water filter Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.