Ultrasonic Dog Repeller Product# DR3402   $28.95  Free Shipping Protect yourself from dangerous dogs while cycling, walking, or jogging with the Ultrasonic Dog Repeller. It produces a high frequency sound that the human ear can not detect, yet it is able to deter vicious dogs without harming them. It's even safe enough to use for training dogs. Features a belt clip and a low battery indicator. Requires one 9 volt battery.