Official Replacement Ultra Filter for Survivor Filter StrawTo replace, simply remove used Ultra Filter and replace with newBeware of imitations and use only Official Survivor Filter replacement parts.Filters down to an astonishing 0.05 Microns, can be re used up to 100,000 liters (26,417 gallons) and can be easily replaced.An O ring helps keep the unit watertight.Ultra Filter is housed in a heavy-duty ABS plastic casing and sits inside the body of the Survivor Filter.