The bottle that comes with the plug in has a wick, and by opeing cap and screwing it into plug in dispenser, the phermones are sent through the air. It is supposed to mimic the scent left when a cat rubs his or her check against something, and is touted to have an overall calming affect.

There is no smell for humans to detect, which I was concerned about because I HATE most fragrances and only use unscented litter.

Good luck with it, and let us know if it seems to help your situation. It is too soon for me to report on my experience, but fingers crossed for success!