Clinically proven to be 88% effective at reducing or eliminating barking. The burst of citronella spray, a unique scent most pets don’t normally encounter, acts on four of your dog’s five senses. Can be used indoors or out. Includes 2.5 oz. anti-bark device, 24" adjustable collar, citronella spray and 3 oz. refill, 6-volt alkaline battery and instructions. Stress-free and gentle enough for both of you.