For a newly anxious dog, a fresh adoption, or ongoing low-level stress, the Adaptil Calm Home Starter Kit is the simplest way in - everything needed to begin pheromone therapy in one box, instead of buying the diffuser and refill separately. The kit contains the electric diffuser unit plus one 48 ml refill, covering up to 50-70 m2 for the first 30 days. The diffuser is reusable and should be replaced every 6 months; refills are bought separately. Adaptil uses Dog Appeasing Pheromone (DAP), a synthetic version of the pheromone nursing mothers produce. Plugged in, the diffuser keeps a steady ambient level in the room, commonly reducing barking, destructive behaviour, and general restlessness. It's odourless to people and doesn't affect cats or other pets. Plug it into the room your dog uses most and leave it running for best results.