Function: 1. Exquisite manufacturing: each ball has been carefully measured, the weight is uniform and consistent, and the uniquely selected base and ball are made of high-quality materials. 2. Long swing time: Classic design, due to air resistance and friction, the balance ball can last 15-20 seconds and has a longer duration. 3. Multiple ways to play: For example, one ball at one end hits the neighbor, the ball at the other end hits the air while the ball in the center stays stationary. 4. Relieve Stress: The ball toy is a cute desk decoration, which can not only add beauty to your room, but also relieve stress when playing. 5. Educational Importance: The balls are also a great school education gadget that can help children understand the importance of saving energy. Specification: Item Type: Balance Pendulum Ball Material: ABS plastic, metal Overall Size: Approx. 9.5x9x7.5cm/3.7x3.5x2.9in Colour: black, wine red Package List: 1 x Base 1 x balance ball