Polar Pure Water Disinfectant uses pure crystallized iodine in a unique delivery system to destroy water-borne pathogens including giardia cysts and micro-organisms (viruses) that pass through filters. Simply add water to your Polar Pure bottle. Does not deteriorate with extremes in temperature. Has an indefinite shelf life. Is safe and fully effective to use as long as you can see iodine crystals at the bottom of the bottle. One bottle treats up to 2000 quarts of water. Dosage chart is printed on the bottle. Bottle cap is used to measure and decant solution -- no other equipment needed. Small size and light weight makes it convenient for backpacking and travel. Essential for emergency preparedness.