Each time your dog barks, the electronic bark-sensing unit, releases a brisk, citronella spray in front of the dog's snout. Your dog hears it, sees it and most importantly, smells it. At the first spray of citronella, your dog's natural curiosity will be to seek the origin of the new odour. The dog will very quickly learn that when he or she barks, the collar sprays! Through this harmless conditioning reflex, Anti-Bark can eliminate nuisance-barking by up to 88%, and dogs will only bark in extreme situations such as emergencies. The citronella spray is 100% safe for all dogs, people and the environment.