Sentry Calming Collar for Dogs is clinically proven to effectively modify stress-induced behavioral problems on dogs. Help your pets feel safe and secure during difficult and stressful situations! This product helps alleviate behaviors that are triggered by anxiety-inducing situations such as being left alone, new social situations, fireworks, and thunderstorms, by releasing calming pheromones mimicking the kind that mother dogs produce to calm their puppies. These pheromones significantly reduce or eliminate inappropriate marking, excessive barking, chewing, scratching and other destructive behaviors. For maximum comfort, this collar features a unique fit and stay design. It also features a breakaway mechanism as an added safety measure should your pet get stuck or hung up on an obstacle. Sentry Calming Collar for Dogs is scientifically proven to be safe and effective, and can be used without long-term side effects. Comes in a soothing lavender chamomile scent. Will work and continue to release pheromones for 30 days. Can be used on all types of dogs in all ages. Fits dogs' necks that measure up to 23 inches.