By emitting a low-frequency, ultrasonic sound, this lightweight, portable light repels mosquitoes while simultaneously illuminating a 20-foot-square area around an outdoor barbecue grill or picnic table. To ward off mosquitoes, switch the device to either of three levels of ultrasonic sounds, which repel female mosquitoes (the biters) by imitating their natural enemies. (The sound will not harm pets or children.)