Sentry Calming Collar for DogsSENTRY Calming Collar for Dogs uses pheromones that are released slowly over time to reduce anxiety in your dogs. It helps keep them calm in situations which would normally cause them stress or fear. It works by using the same pheromones that mothers use to calm her puppies. While the pheromones will be released immediately upon putting the collar on your dog, please give two weeks to a month to see full benefit. SENTRY's sustained release pheromones