The 45 piece Building Box is Hubelino’s most compact marble run kit. The brick selection is optimized for creating interesting smaller marble runs. The set is an intuitive introduction to the Hubelino system containing everything you need to get started: a base plate, building blocks, marbles and a booklet with sample tracks and instructions. All Hubelino products are 100% compatible with Duplo bricks and are produced in Germany where they are tested to all European and US safety standards for toys. Hubelinos marble run products promote spatial intelligence and an elementary understanding of physical principles. Thanks to age-appropriate difficulty levels, builders young and old can take an exciting trip into the world of physics. WARNING: CHOKING HAZARD — Toy contains a marble. Not for children under 3 yrs.