The PetSafe® Little Dog Deluxe Spray Bark Control Collar effectively deters barking when it is worn. The Bark Control Collar has a unique patented sensor that provides the most reliable bark detection available. The Bark Control Collar uses both vibration and sound sensors (patented Dual Detection) to discriminate each bark from other external noises. A burst of citronella spray is emitted to deter barking only if both the vibration from vocal chords and the sound from the bark match the same criteria.