Release the inner engineer. Our Pulley 90 Set is a perfect introduction to the world's most powerful engineering principles and lays the foundation for future STEM-Learning. This Pulley set includes 4 more tires and which gives more creative freedom than any other pulley sets. Build up to 8 different working real-world contraptions. Our pieces connect anywhere, any time, under any angle. Try it! As parents, we want to give our kids an advantage. This pulley set combines play with learning and develops their skills as builds become more complex and advanced. Only the best is good enough. That's why we have third parties rigorously test our pulley sets for safety. Plus, all pieces are Certified Non-Toxic, BPA-Free, Lead-Free and Phthalates-Free. This kit is designed specifically for the classroom supporting up 4-6 students at one time. The large pieces are easy for students to build with. Includes access to 25+ free online lessons and activities.