The Thermacell Mosquito Repeller 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. Each Original mat provides up to 4 hours of repellency Refills work with all Thermacell repeller devices (Repellers, Lanterns, and Torches) Refill pack includes 12 repellent mats and 4 butane cartridges for 48 hours of repellency