Take this pocket sized device on fishing trips, camping, or picnics, anywhere you are bothered by pesky mosquitos. This safe, non-toxic mosquito repeller works by emiting a continous ultrasound frequency which keeps away the females, which are the ones responsible for biting. It works with a 9v battery (not included), has an on off switch, indicator light and an adjustable frequency. Perfect for people sensitive to chemical fly killers or odours.