SmartMax is the magnetic discovery concept that enables children, even from a very early age, to experience both the wonders of magnetism and the fascinating world of construction in a safe way. SmartMax bars have a unique color code. Cold colored bars attract warm colored bars and repel other cold colored bars. Warm colored bars repel other warm colored bars. Longer bars have stronger magnets than shorter ones. SmartMax Vehicles are also magnetic, and click in place. Mix and match with other SmartMax building sets, sold separately. With this set you can build an entire fleet of trucks. Ages 3 and up.