The Bark Free device emits a tone that dogs but not people can here. It is unpleasant to them and distracts them from barking. Unfortunately the sound can also be triggered by loud noises such as trucks or door slams. This punishes the dog for something he didn't do.
The Bark Free device works by emitting an ultrasonic sound that cannot be heard by humans. When a dog barks within range of this device, the device blasts a sound back at the dog that will deter the dog from barking again.
I believe the collar shocks the dogs, when it feels the sound vibration in the dogs throat. I honestly believe there are better ways to prevent barking.
It's basically a electrical collar that you just place around the dog's neck, and when the dog barks, you use a remote control to give a little shock or poke to correct the dog's behaviour.
