Comfort Zone Calming Diffuser Refills Refills fit Comfort Zone Diffusers with Feliway and Feliway Diffusers Mimics cat pheromone that helps with cat calming Helps reduce urine marking and unwanted scratching Satisfaction guaranteed or your money back Comfort Zone products with Feliway are clinically proven to be 90% effective Replace Comfort Zone with Feliway refills every 30 days Veterinarian Recommended, Drug Free, and Unscented One refill covers up to 650 sq ft