Feliway Friends Refill is designed to be used with Feliway Friends Diffuser. The diffuser helps avoid conflict and develop harmony between the cats in your home and reduces the signs of conflict. The solution diffuses cat-appeasing hormones called pheromones that help prevent fighting, chasing, blocking, and staring between cats, enabling them to get along better. One refill pack lasts for up to 30 days. Use Feliway Friends to develop friendship and cooperation between cats.