I've used the shock type collars and would again if needed. They have 12 degrees of probe so if the dog barks it merely senses a very light buzz. If he continues to bark the degree of the buzz increases by itself. So if the dog decides on an all out ferocious bark he would feel the higher probe. It works by the higher density of the bark. Mine only barked once and they were so puzzled the didn't bark again. I think I've resorted to it 5 times at most. The nice thing about them is that once the dog knows about the collar you can tape an old square battery to any collar and he will think it's the bark collar and won't make a sound.