The PlanToys Gear and Puzzle set lets your child be an engineer and create a gear system of their own design. The gears can be placed together in whatever pattern your child desires. Once they are connected, You can spin the main gear or any of your choosing and watch the unique movements based on the gear pattern you created. Watch in amazement as the gears spin and twirl as they move adjacent gears with their interlocking teeth. The set comes with 22 pieces total.