The Thermacell Patio Shield Mosquito Repeller is a compact and stylish device will look great on any patio or deck while it works to repel pesky mosquitoes. Ideal for use while entertaining. Thermacell Patio Shield is powered by a Thermacell fuel cartridge which creates heat to activate the repellent Allethrin, a synthetic version of a naturally occurring repellent found in chrysanthemum flowers. Heat disperses the repellent creating a 4.5 meter zone of protection. Thermacell protects millions of people from mosquitoes with no messy sprays or lotions, no scent, no noise, no DEET, and no open flames. For best results, use on days with light or no wind (bugs are at their worst on these days), and allow 10-15 minutes to form a complete zone of protection. Thermacell products are safe, effective, and come with a 100% Satisfaction Guarantee. With Thermacell, Turn it on… Mosquitoes Gone!