2 Oz. Lotion 12 HOUR Ultrathon® is the longest lasting and most effective insect repellent on the market today. It repels mosquitoes for over 12 hours and ticks for over 9 hours, and is also effective against biting flies, gnats, chiggers, and fleas. Ultrathon® contains 34% DEET in a controlled-released polymer. Moisture resistant - lasts through splashes, perspiration, and rain. Used by the U.S. military because of its effectiveness. Also repels terrestrial leeches in tropical areas where pests occur.