UGears Dynamometer is a dynamic and unique model. It operates using the pneumatic principle by making use of air to wow the user. This UGears model operates by transforming air pressure into motion. When you blow onto the top gear a system of lever spins the wheel of the arrow. One interesting thing about this model is that it can be used as a game between your family and your visitors. You blow on top of the gear and the arrow spins and comes to rest on a particular task that the blower will be asked to perform. It is a good educational model. The Dynamometer is one of the simplest UGears model, however it shows many basic principles of mechanics, including the cascade of gears and the mechanical junction known as the Geneva drive. It is crafted from high-quality plywood boards, using precision-cut parts. The whole model is just 48 units and it can be assembled in 1-2 hours following the detailed instruction manual. Ages 14 & up. 48 pieces. Level: easy.