Nutri-Vet Pet Ease Cat - This pheromone diffuser is great. Excellent for cats who have high anxiety, stress, or some behavioural issues. Just plug it in in the room that your cat spends the most time in, and let the diffuser go to work. I have to buy a refill monthly on average, but I find how often I replace it depends on the climate. Helped one of my cats stop peeing on everything.