Ultrasonic animal chasers are the most humane and environmentally friendly way to keep potential pests out of your garden this new ultrasonic repeller provides 24 hour protection from those garden pests quoted as the most effective method of driving cats from gardens by dr bradshaw of southampton university r r 3 switchable frequenciesr deters cats dogs foxes squirrels deer vermin insects rabbitsr 3 switchable volumes high medium low r twin high power transducers give 12db u