Builds 7 different replicas of real-world models, one at a time. Set includes color-coded building instructions with real-life photos and key facts for each model. Models demonstrate 2 spur gear examples, 2 crown gear examples and 2 sprocket gear examples. 198 K’NEX Rods and Connectors support 2-3 students working as a team. Come packaged in a strong plastic storage case with movable dividers and transparent lockable lid.