Build a classic, nostalgic KNEX model just like you remember with the 20th Anniversary Big Ball Factory; After 20 years in the KNEX vault, we are bringing back this classic model to thrill our most loyal fans. Over 3,100 Classic KNEX 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. Size H35.56, D55.88cm. Batteries required: 2 x AA (not included) plus . For ages 12 years and over. WARNING(S): Not suitable for children under 3 years old. Only for domestic use. To be used under the direct supervision of an adult.