Lifesystems Endurance 12 Hour The Endurance insect repellent is specially formulated with a unique time-release agent that enables the DEET to evaporate at a much slower rate. This provides effective protection for up to 12 hours whilst using a lower concentration of DEET than standard repellents. Active Ingredient(s): 34% DEET. Repels: Mosquitoes, midges, horseflies, sandflies, gnats, fleas, ticks and other biting insects.