Thermacell Mosquito Repellent Refills Earth Scent –This refill value pack includes 12 insect repellent mats and 4 butane cartridges, providing a total of 48 hours of repellency and cover scent. They fit Thermacell Fuel Powered Repellers. Features 12 insect repellent mats 4 butane cartridge Each cartridge lasts up to 12 hours Each mat lasts up to 4 hours Refills can be stored for long periods of time Cartridges and mats don't need to be used all at one time If time between uses is more than a 1 week, store the mat in a dry, dark place Repellent: Allethrin