From Manufacturer:  Made of the highest quality construction, this robust water filter is ideal for long lasting continuous use, even under extreme circumstances. The filter’s silver impregnated ceramic element is effective against bacteria and protozoa, using a Micro Filtration method. Up to 1 quart (1 liter)/minute Cartridge Capacity, up to 13,000 gallons (50,000 liters), depending on water quality. This pocket water filter is a favorite of outdoor enthusiasts, international travelers, and the U.S. Military. Includes: Hydration Accessory, Prefilter, Bottle Clip, Carry Bag, Measuring Gauge and Cleaning Pad This item was purchased in 2012, but has never been used. Has been stored in carry bag, accessories are still in the original bags. Some scratches on prefilter weight due to being held in the case, but will not affect performance.