Need good Bark Collar

I use the Dazer II...it has an ultrasonic high powered sound when activated by the user...we have a chihuahua with anxiety issues...we have tried obedience school...water bottle spray ...pebbles in a plastic bottle to redirect her attention...herbal meds...nothing worked until this...I have only had to activate it a couple of times....and never more than one push....now she will give a wee bark and then look over at me then she just lays downs or continues on looking around...
It is wonderful for aggressive dogs on the street and will come in handy in Ecuador where street dogs abound ! It is very reasonably priced and worth its weight in gold in my opinion...we now have a quiet home .

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