Instincts by SmartyKat® Mouser Mayhem™ set of 2 releases your cat’s inner instincts with HappyNip® catnip and silvervine-shaped mice. HappyNip®, our proprietary blend of catnip and silvervine, is an extra-exciting natural cat attractant. Cats who don’t react to catnip alone will have a reaction to HappyNip®, making it the perfect blend to entertain your little hunter. Encouraging your cat to frolic, romp, and play!