The square is a public leisure place, and its main activities are tourists, as well as bicycles, wheelchairs, baby carriages and so on. Also allowed to enter. But for the sake of safety, most squares are closed to motor vehicles. In order to effectively block the entry of motor vehicles, it is necessary to set up motor vehicle isolation facilities, and stone balls are one of them. Compared with the previous upright isolation columns and one-way doors, the stone ball isolator greatly reduces the obstruction to pedestrians. Non-motor vehicles can pass easily, and the possibility of being damaged or moved is very low, which can effectively block motor vehicles. At the same time, it is beautiful, weatherproof and environmentally friendly, and pedestrians can also rest as stools. So many city squares use stone balls as isolation facilities for motor vehicles.