Feature: 1. Exercise Children's Ability: This scientific car model can train children's logical thinking ability and practical ability, which is suitable for children's early development. 2. Experimental Principle: The experimental principle of the scientific car model is that the shaft connecting the rear tire of the pull back car is fixedly connected with the pull back gear. 3. Kinetic Energy is Transformed Into Potential Energy: When the hand is pulled backwards, the wheel rotates backward, and the force is transmitted through the shaft to the pull back gear to perform work. 4. High Quality Material: This toy is made of composite wood, safe and non toxic, sturdy and durable, suitable for children to play, ensuring a long service life. 5. Best Gift: An exquisite gift for children that can attract children's attention and is a parent child project to accompany children's growth. Specification: Item Type: DIY Pull Back Car Material: Composite Wooden Appropriate Age: 6 Years Old +. Package List: 12 x Tire3 x Pull Back Tooth Box3 x Small Iron Rod3 x Wood Board