The Thermacell cartridge refill effectively repels mosquitoes by creating a 15 ft zone of protection when used with thermacell devices and thermacell repellent mats. Use this fuel-only refill for when you have spare thermacell repellent mats. Features: This 4-pack provides up to 48 hrs of use in thermacell mosquito repellers Fuel-only refill, repellent mats not included For use in fuel-powered thermacell repellers, lanterns, and torches Can be stored for long periods of time Package contains - (4) fuel cartridges each lasting 12 hrs