Thermacell Backpacker Mat-Only Refills effectively repel mosquitoes by creating a 15 ft zone of protection when used with the Thermacell Backpacker Mosquito Repeller. No spray and no mess. Scent-free and DEET-free. This Refill does not include fuel cartridges. Active ingredient is Allethrin, a synthetic version of a naturally occurring repellent found in chrysanthemum flowers. Includes 48 hours of mosquito protection refills, package contains- 12 repellent mats lasting 4 hours each.