Plan Toys X-Track Expansion Set Plan Toys X-Track Expansion Set lets kids connect and link various tracks to build bigger cities. Designed to promote natural learning, these X-shaped track pieces create a landscape for innovative and creative learning. Why You"ll Love It: This city gets bigger as the fun builds up. Age: 3 years and up FeaturesCan be expanded with existing setsMade of rubber wood Fosters creative learning Encourages healthy social interaction Comes with easy-to-grip accessories