Crystal Quest Whole House Double 20" x 2.5" Water Filter System GAC is universally recognized and widely used as an effective adsorbent for a wide variety of organic contaminants, such as chlorine (99.9%), chemicals linked to cancer (THM's, benzine) pesticides, herbicides, insecticides, volatile organic compounds (VOC's), PCB's, MTBE's and hundreds of other chemical contaminants that may be present in water that create bad taste and odors. Eagle Redox Alloy (ERA) is a major advancement in water treatment technology that works on the electro-chemical and spontaneous-oxidation-reduction (REDOX) principles. Chlorine is instantaneously and almost inexhaustibly oxidized. Multi Stage conveniently provides 80,000 gallons of quality water. Great for homes, apartments or office use. Pressure Release Valve Built-in Wall Bracket Available at 1/2", 3/4" or 1" NPT input/output Easy Filter Changes Compact