PetSafe® collar with rattle spray effectively interrupts rattling. The sound and vibration of the dog's skull triggers the sensor that gives the dog a spray.The collar is safe and interrupts barking by distracting the dog.Facts about PetSafe Spray Anti-snoring Collar:Effectively interrupts barking dogs.Approximately 35-40 sprays per cartridge.Water repellent.Indicator light for low spray level.Includes two spray cartridges (1 citronella + 1 neutral).USB charging.Fits dogs from 3.6 kg and up to 68 cm in neck circumference.