1. With the blue caps in place wash the exterior of each fluoride filter Elements with water and mild dishwashing soap, then rinse. With clean hands, remove both blue caps from each end of both filter Elements.2. Place the rubber priming button (tan colored) onto one end of a fluoride filter and align the hole of the filter with the hole of the rubber washer. Press the priming button up against the sink faucet so that the priming button creates a seal between the faucet and the Fluoride Filter. Place your thumb on top of the faucet to apply pressure, to create a better seal (as seen in picture).3. While holding the priming button against the faucet, turn on the cold water slowly, allowing water to fill the cavity of the filter and flow from the opposite end. Allow water to flow for at least 30 seconds or until water runs clear.4. Turn the Fluoride filter over and prime the opposite end (reversing the flow of water) repeating steps 3-5 until water runs clear from both directions.5. To determine if the filter is fully primed, collect the filtered water in a clear glass and hold it up to the light to see if all of the cloudiness is gone from the water, if not continue priming until water is clear. This filter is now primed and ready to install. Repeat priming steps 1-7 for each additional Fluoride Filter.[High-efficiency Filtration]: Replacement for PF-2 fluoride filters effectively reduce fluoride and arsenic, absorb odor, color, residual chlorine, heavy metals, they also reduce sediments and large particles effective in improving tasteColour:WhiteMaterial:plasticPackage Contents:2 x Water Filter1 x Rubber ringOnly 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.