Citronella Anti-Bark CollarPatented Technology and Scientfically Proven Most Effective Bark Solving MechanismThe Citronella Anti-Bark Collar is the most humane and effective nuisance barking solution. It delivers a harmless burst of citronella to interrupt your dog's barking. Scientifically proven to be twice as effective compared with electric shock collars. Citronella Anti-Bark Collars can be used with any dog which is at least six months old and weighs at least six pounds. The collar is adjustable up to 24" so it can accomodate even the largest of most breeds, and weighs only 2.5 ounces so its safe for small dogs as well... Everytime your dog barks, the electronic bark-sensing unit releases a harmless burst of citronella in front of your dogs snout. It is so effective because of two main reasons. 1st, it's an immediate form of re-inforcement. Your dog is told by the collar that his barking is not welcomed, as he is corrected by the harmless citronella spray. 2ND it works quadruple time as it effects four of your dogs senses, he hears it, he sees it, he feels it, and he smells it. The collar is also entirely self-sufficient. Meaning you simply fill it up with citronella, put it on your dog, and the collar takes care of correcting the unwanted behavior, you don't even need to be present. The Citronella Anti-Bark collar is the only anti-barking collar recommended by leading animal experts.