Propel the marble through your run by adding the Hammer. When triggered, the Hammer swings down and strikes the marble, giving it momentum to send it on its way. Including the hammer tile and 6 additional tracks, this accessory must be combined with the GraviTrax Starter Set. GraviTrax is a modular, electronic-free interactive track system where you can design and build your own marble runs. This STEM toy for boys and girls 8 and up, encourages experimenting with gravity, magnetism, and kinetics to propel your marble to the finish. Designed with open play in mind, the concept offers endless possibilities to design a different track every time you play. Expand your builds and add some action with a variety of expansion sets and accessories.