This toy can be shaken back and forth by a nudge from cat. The bottom of the toy is designed with a weight, so the toy will not fall. When the weight move back and forth, the two balance wheels will also move back and forth to attract more interest of the cat.it can complete 180 degrees self-swing, 360 degrees rotation, rolling, can play in any state. Built-in self balancing system design make the ball change direction automatically when colliding with a wall, chair, door, etc. No need for additional help.It can be used for multiple cats at the same time, which can effectively improve the intelligence of the cats while they are learning how to play.Customized is available.