Add the dimension of sound to your Quadrilla run with a xylophone rail that plays a musical scale as your marbles race over it. Multiple marbles means multiple scales will sound simultaneously for a cool sonic effect. Helps to develop spatial thinking and an understanding of Science, Technology, Engineering, Art and Mathematics (STEAM) 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.