Emergency water filter system for hiking, camping, and emergency situations. Effective on protozoan cysts. (Giardia and Cryptosporidium) Use with Aquamira Water Purifier Tablets or Water Treatment Drops for a complete system. Economical - 1 system filters up to 20 gal. (75L) of water. Ultra light and compact. (weighs less than 1 oz. < 5" long) Perfect for emergency kits, foreign travel, back country, and outdoor activities.