Dog Barking Control Devices 3 Frequency Levels Automatic Ultrasonic Adjustable 3

Sensor distance up to 33 feet. The dog is stimulated by the sound and will stop barking. Suitable for all breeds and sizes of dogs. PORTABLE: Ultrasonic barking deterrent is designed to look like an alarm clock, it can be hung from a tree, anywhere in the house or in your yard, it can be hung, placed on a table or anywhere else.

eBay