Set of 330 pieces. Set includes rods of 6 different proportionate sizes in 6 different colours and balls in 6 colours. The balls have fitting holes to allow the rods to connect at various points. What can be built is only limited by the childs imagination. Challenge your child to build a strong structure that will not topple even if dropped. Or build their own design of a bridge. Useful in both STEM and STEAM lessons.