The Thermacell Mosquito Repellent system effectively repels mosquitoes, black flies, and other biting insects by creating a 15 x 15-foot zone of protection for bug-free comfort. Ideal for use while you are camping, hunting, fishing, gardening, and around the backyard, Thermacell products have been evaluated by the EPA for safety and effectiveness. FeaturesInsect protection for up to 120 hours30 insect repellent mats last up to 4 hours each10 butane cartridges