Ultrasonic Dogchaser LS-977 Probably the most human and safest way to stop unfriendly dogs, can also be used as a dog training device. The ultrasonic dog repellent transmits frequencies in the range that is barely audible to humans, but can be heard by dogs (can also be used with cats), effective range approx. 5 - 6 m, small, compact, black hard plastic housing with retaining clip, red LED power indicator, frequency range 20,000 - 25,000 Hz, sound pressure 135 dB, powered by 9 V block battery (not included), dimensions 94 x 60 x 27 mm, weight 53 g.