As seen on TV - GraviTrax is an innovative marble run and contruction toy for boys and for girls ages 8 years and up. It is an ideal christmas gift or birthday gift for smart, curious kids. The GraviTrax Hammer will add some much-needed velocity to your track layout. Innovative - The GraviTrax interactive track system allows you to design and build your own race tracks and experiment with engineering, gravity, magnetism, and kinetics to propel your ball to the finish. Infinitely Expandable - Gravitrax in fully expandable with a large range of expansion pack and accessories! An amazing building toy! Develops critical skills – Playing and building with GraviTrax builds spatial reasoning and planning skills, and provides a great stealth learning experience. Clear instructions – Comes with clear instructions so that you can start construction and start playing with this fun brain game within minutes, Manufacturer: Ravensburger