This weighted marble building & tracking set is a fun, effective way to develop motor skills and hand-eye coordination for children. Rollipop set includes 5 tracking balls and ramps for endless fun. It'll challenge young minds and develop those critical thinking skills - all while having a blast! Baby & toddler tracking toys complete with 5 weighted tracking balls. The best architects need to start young. Safe for ages 9 months and up, this marble and tracks set is ideal for developing and effect, creativity and eye- hand coordination. 3 lbs.. Includes five weighted tracking balls Only tracking toy in the industry tested and approved for Ages 9 months. Promotes motor skills, logic and reasoning, hand eye coordinationand visual sensory development