Original Thermacell Mosquito Repellent Refills effectively repel mosquitoes by creating a scent-free 15-foot zone of protection when used in fuel-powered Thermacell Repellers. Ideal for use while you are camping, hunting, fishing, gardening, and around the backyard. Includes 12 hours of mosquito protection refills For use in fuel-powered Thermacell Repellers, Lanterns, and Torches Each repellent mat lasts up to 4 hours and each fuel cartridge lasts up to 12 hours No spray and no mess. Scent-free and DEET-free. The active ingredient is Allethrin, a synthetic version of a naturally occurring repellent found in chrysanthemum flowers