This ThermaCell Mosquito Repellent Refill is specifically intended for use with ThermaCell Mosquito Repellant Appliances. This single refill comes with three insect repellent mats and one butane cartridge refill, that is enough to provide 12 hours of protection from mosquitoes, black flies, and other insects. This refill kit can be stored for as long as you need, you never have to worry about it going bad. When you are ready to refill your appliance, simply slide in the net mat and butane cartridge, then hit the button to restart. If you plan to not use the device for more than a week, it is recommended that you remove the mat for storage.