For the backyard and beyond, the Thermacell E-series is easy to use and provides hours of scent-free, mess-free mosquito defense. Our most advanced repellent available, the E55 provides a powerful zone of unbeatable area protection from mosquitoes. Features a 5.5-hour battery. 12 hours of mosquito repellent included. Audio cues and LEDs let you know it is working and how much battery life remains. Keep mosquitoes away with the simple push of a button.