Not a marble run, Rollipop Advanced is an Infant & toddler tracking toy. Infants and toddlers use tracking for visual memory and depth perception as they learn to use their eyes to direct and coordinate their body's large muscle groups and is a necessary skill required to read! Rolli-Pop Advanced is designed to develop this crucial skill using weighted balls that roll down slower than gravity would dictate... you just can't take your eyes off of it! Set includes: 5 weighted tracking balls. 19' X 19" X 11". Develops Fine/Gross motor Skills, Logic, Reasoning, Tracking, Hand-Eye Coordination and Auditory Sensory Development.