Escape from the rotary tower with this exciting Quadrilla set featuring two transparent vertical stairways. Watch as the marbles trip their way down each stairway and shoot out onto the rail. To celebrate their escape, they will ring the three hanging bells. Brings new dimensions of sight and sound to your marble runs. Helps to develop spatial thinking and an understanding of Science, Technology, Engineering and Mathematics (STEM) principles. Praised by the Wall Street Journal as the perfect toy for teaching children how to code. Compatible with all Hape Quadrilla sets. For ages four and over.