OKO Level-2 filtration, originally developed through a NASA grant for space stations, is now available for consumer use. Simply put, it is the state-of-the-art in water filtration technology. Our patent-pending Upstream Valve returns any backwashed fluid into the "unfiltered" water area for re-filtration and to ensure that every sip is pure, fresh and clean. In addition to a 2 micron pore size, the material utilizes a positively charged electro-adsorption (attraction and retention) process to draw and trap harmful agents much smaller than its pore size. Charge fields, activated upon water contact extend 1micron each to virtually close the pore to any intruding agents. Using built-in silver ions, the material then kills bacteria upon contact. A stack of over 400 such pores in the 0.8mm thickness of the filter create a "tortuous path" which a harmful agent would have to travel through in order to make it across.