Build 8 different replicas of real-world models, one at a time. Set includes building instructions with real-life photos and key facts for each model. Models demonstration 1st, 2nd and 3rd class levers along with fixed, movable and combination pulley systems. 178 K’NEX Rods and Connectors support 2-3 students working as a team. Comes packaged in a strong plastic storage case with dividers and lockable lid.