FELIWAY Optimum is a new pheromone discovery, and the best FELIWAY answer to help reduce common signs of stress in cats such as: scratching, urine spraying, tension and conflicts between cats, fears, and reactions to changes 93% of cat owners report enhanced calming, with an average satisfaction rating of 9.1 out of 10 FELIWAY Optimum is a drug free solution that helps cats with more signs of stress, in more situations, and calms cats better than ever; FELIWAY is supported by 25+ years of feline stress expertise FELIWAY Optimum Refill covers up to 700 square feet; make sure to plug your diffuser in with the vents up, and for the best results, position the diffuser where your cat spends most of his or her time - avoid plugging the diffuser in under shelves and behind doors, curtains, or furniture This product includes 1 refill that will last for up to 1 month (diffuser not included); you must use a Feliway Optimum diffuser with this refill (do not use with a different diffuser); to maximize effectiveness replace the refill once a month and the diffuser every 6 months