Kids learn about the physics of levers and linkages as they build 10 out-of-this-world machines and make them work! The kit guides kids through the building process and experiments, helping them create an alien snake-bot, a grabber claw and more. Kit includes 138 building pieces and a full-color 40-page manual with illustrated step-by-step instructions. Largest piece measures 5 7/8" in length. Requires 2 “AA” batteries (not included).