Stock up on your Thermacell for a season's worth of repelling mosquitoes with this Mega Pack. Use the cartridges independently or in conjunction with the mats to repel mosquitoes from an entire zone. Each mat and each cartridge repels mosquitoes for roughly 4 hours and 12 hours respectively. The cartridges fit most compatible repellent appliances and lanterns. Both the mats and the cartridges contain a potent synthetic copy of allethrin, a natural mosquito-repelling ingredient found in chrysanthemums. The mats are quite user-friendly and safe, requiring no fire or wax to ignite.