8 years & up. Build your very own large, hydraulic hand with this interactive science kit! The hand is made up of over 200 pieces, with water filling the piston tubes that allow the mechanical fingers to open and close with your own fingers. Learn all about hydraulic and pneumatic systems and how they are used in industrial robots. Includes 203 pieces and a 40 page manual to guide users through the building process and provide them with scientific information.