Build a classic, nostalgic K'NEX model just like you remember with the 20th Anniversary Big Ball Factory! After 20 years in the K'NEX vault, we are bringing back this classic model to thrill our most loyal fans. Over 3,100 Classic K'NEX pieces complete this gigantic ball machine that stands over 4 feet high! Watch as the 4 balls travel down 4 different paths - which way will the ball go next? Now featuring a motor, just turn the ball machine on and watch it go! Included are easy to follow instructions. You can even download instructions for an incredible Ferris Wheel model. Models can be built one at a time. Requires 2 "AA" batteries, not included. Perfect for advanced builders ages 12+.