Thermacell Patio Shield Mosquito Repeller with 48 Hours of Mosquito Repellent provides legendary defense against mosquitoes, thanks to an invisible, 15-foot zone of protection. The Thermacell Patio Shield Mosquito Repeller comes with four fuel cartridges and 12 repellent mats that produce a total of 48 hours of freedom from mosquito bites. The Patio Shield Repeller uses an interior-heating element to activate the mosquito repellent contained in the blue repellent mat. The repellent creates a zone of protection that stops mosquitoes before they can get close enough to bite. The efficient design of the repeller means no open flame, no recharging and no cords. The unit's compact, lightweight size makes it blend beautifully into your outdoor space and easy to store. Scent-free and spray-free, the Thermacell Patio Shield Repeller creates an ideal mosquito-free zone so the whole family can enjoy the outdoors on a patio or deck. Evaluated by the EPA for safety and effectiveness and comes with a 100% satisfaction guarantee. Turn it onâmosquitoes gone!