Abracadabra, presto, chango — your marble run just added some colorful, magical fun with the “GraviTrax Color Swap” accessory! Bring a new element of surprise into your GraviTrax marble run! As if by magic, the marble changes color as it passes “through” the “Color Swap”. Simply hide a marble within the tunnel — the momentum from the incoming marble propels the hidden marble out the other side with the illusion the marble changed colors! It’s a snap to combine “Color Swap” with any “GraviTrax Starter-Set” to experience the power of gravity and educational fun today! What makes a great toy? GraviTrax checks all the boxes! It’s a creative, modular, expandable track system that challenges children to use their imagination to design and build their own marble runs! GraviTrax construction sets use STEM-friendly concepts while building critical thinking and problem-solving skills. Completely open-ended, every GraviTrax set has a boredom-busting variety of play options for hours of fascinating fun. Once the basics are mastered, simply add expansion sets and accessories to propel those metal marbles around the tricked-out track of your dreams! Comes complete with instructions, 3 Color Swaps and 3 marbles (red, blue, green).