Bark Control Collar The product is controlled by a microprocessor, distinguishes your dog's bark from other environmental noises and automatically delivers sound and shock stimuli after each bark. The output level of sound and shock is gradually increased as barking continues, giving your pet plenty of warning before it becomes painful. The collar should fit snugly underneath your dog's neck. Low battery consumption. Power by a 6 volt battery size 2/3 AA LED Flash signal light., Voltage aduster