Desk Table Decor Metal Cradle is an excellent educational science gadget. Not only demonstrates a pendulum, but it also shows the laws of conservation of momentum and energy. Pull back one or more of the balance balls, release them and the same number of balls will swing up on the opposite side. Great for home ornament, study or office desk table decor accessories, etc. Also good for a birthday gift and a kid's toy. Style: Modern Material: Metal