I gave this 5 stars because these diffusers have always worked for us on numerous occasions. I tend to use them when I foresee an upcoming stressful event for the cats such as: out of town company, moving furniture around, any outside stressor that I can predict, and for my one bully kitty who likes to tease. I recently had to move some litter boxes around to different locations and used the diffuser during a one month transition. I found that not only did it help with the change but Wendall's urge to tease seemed much less. My other cat, the one who get teased, always seems more confident when I have a diffuser plugged in and less likely to get upset. I don't use them all the time just on a case by case basis but certainly glad to know they are always available for back-up with any stressful kitty situation at home.