Scientifically proven to modify canine behavioral problems caused by stress or fear. The Sentry Calming Diffuser employs Good Behavior Pheromone Technology to prevent excessive barking, whining, chewing or marking and ensures your pup stays relaxed after you've left the house. Created to mimic the pheromone produced by mother dogs to calm their puppies, this technology creates a soothing, anxiety-free atmosphere that covers an area of 215 ft. and lasts up to three months. Convenient plug-in diffuser is compatible with any U.S. electrical outlet. Sizes: 1.5 oz., Refill.