Kullerbü is a flexibly expandable play system that consists of wooden tracks and supports, plastic connectors and curves, bridges windmills, dominoes, tactile smooth wooden balls, both free-wheeling and motorized vehicles and so much more!. The suggested age range is 2 to 8 years old, however older children and adults will be inevitably drawn into the fun. There really is no right or wrong way to build a Kullerbu set though the options increase greatly with each expansion piece added. Your layout may not work perfectly on the first try and that is OK! Problem solving is encouraged and makes success even sweeter! In addition to carefully selected materials and high-quality craftsmanship, the issue of safety is of highest priority at HABA. Kullerbü products, like all HABA wooden toys, pass through our in-house safety tests as well as external test procedures to meet all US and European safety standards.