No-Stress Absolutely Fabulous! I have three cats,one female 11 years old and two males- one 6 and the other 5 . I believe the male cats feel they are playing but behavior is very aggressive. My female does not want to play anymore but the boys keep attacking her, especially, right after she uses the litter box. It was a miracle! I believe there was a change after the first day. I would recommend this to any one who has aggressive issues. My house is so calm and peaceful now I can’t believe it. This is truly a great product.