These refills are for use with FELIWAY diffusers. FELIWAY CLASSIC is a clinically proven solution to help comfort and reassure your cat at home. It works by mimicking calming messages that cats naturally release in the air called pheromones. These messages help cats and kittens adjust to changes in their environment, feel comfortable in a new home and avoid unwanted behaviours like urine spraying, scratching and hiding. Trusted by veterinarians and pet owners worldwide for over 25 years, more than 14 million cats have benefitted from FELIWAY cat pheromone products.