 It's the official launch of Harmony PetLine brought to you by Tevra Pet. Harmony PetLine is a new innovative product for cats and dogs designed for behavior modification using cutting edge pheromone technology designed to calm your furry friend without any hassle. Simply remove the back, open and use. No plugs or heat needed. And here's the best part. Harmony PetLine products are two and a half times more effective than other calming solutions on the market.