Create a 15' bug free zone around you so you don't have to hunker in a bug shelter or try to enjoy life through a headnet while you're outside. Thermacell works by heating pads containing D-cis/trans allethrin as the active ingredient. The Backpacker is compact and lightweight, and you simply snap it onto a regular fuel canister (just like your backpacking stove), insert a pad and turn it on. It takes hardly any fuel so you can have it on for hours at a time. Note: fuel not included.