Protects horses against horse flies, face flies, gnats and mosquitoes that carry West Nile virus. Unlike most repellents available today which are based on permethrin and/or pyrethrum, Outlaw contains the breakthrough chemical cypermethrin. Outlaw contains six times as much cypermethrin as other leading brands.Controls 45% more biting flies, gnats and mosquitoes in the first 24 hours than other leading brands.