The Feliway Friends diffuser is developed specifically for households with more than one cat. The diffuser emits an odourless pheromone: the Cat Appeasing Pheromone (CAP). This pheromone is naturally produced by a nursing mother to make her kittens feel safe and secure, and to promote a bond between them. Feliway Friends helps reduce tension between cats and restores the balance in multi-cat households. The starter kit contains a diffuser and a refill. Refills can also be bought separately. The Feliway Friends and the Feliway Classic can be used simultaneously when you notice that your cats display other behavioural problems as well, such as urinating in the house, fear and scratching.