Cool Runners Citronella Anti-Bark Dog Collar Includes 1 x spray control receiver and collar 1 x 3.1oz.; Citronella spray refill 1 x 6-volt alkaline battery 1 x operations manual This unique dog collar is equipped with a battery-operated, electronic bark-sensing unit The adjustable collar releases an all-natural citronella spray when your dog barks The harmless citrus smell and quick action of the spray mist startles and confuses the pet's highly developed senses While not harmful, it is a sufficient deterrent to excessive barking