The gift that inspires. A great way to get your kids or grandchildren interested in the principles of physics, engineering, and math. Like "The Crank", this spiral toy is hand-powered but twice the fun. Marbles go up the center elevator then race down both sides. Each toy is made by hand and therefore unique in wood grain, color and characteristics. Dimensions: 3 1/2"D, 8 1/2" W, 16" H The toy is made from a combination of Vermont Maple and Mahogany. This toy comes with 32 self contained marbles .