Newton's Cradle (4-3/4" H X 5-1/2" W X 5-1/2" D) Entertaining Desk Accessory Metal Newton Cradle on a Black Wood Base Demonstrates conservation of momentum and energy via a series of swinging spheres Product Size: 4-3/4" H x 5-1/2" W x 5-1/2" D also available in smaller size Packaged in a Cardboard Box