The Comfort Zone Multicat Diffuser decreases the frequency and intensity of tension between multiple cats. This product also helps cats live together more peacefully in a multi-cat home. You will start seeing results in a week. To use simply plug in the diffuser in a room where the cats reside and replace with a refill every 30 days - Contains (1) 48 mL refill - Diffuser sold separately; fits both Comfort Zone and Feliway brand diffusersUnited States