Works like magic…but it's science! Harmony Pet Dog Calming Collar features P.E.T. Calming pheromone which is scientifically proven to help calm dogs during stressful situations. Harmony Pet's calming collar continuously releases the pheromone for up to 30 days keeping dogs relaxed and focused at home and on the go. Harmony Pet's calming pheromone has been clinically studied and proven to be 2.5 times more effective than leading brands in reducing stress.