Usage Tips:Purpose: This machine is used for the basic structure and working principle of AC and DC generators in the teaching of junior high school physics and elementary school natural knowledge. Structure: This inst ent is a permanent magnet, rotatable armature generator, composed of a stator, a rotor, brushes, a base plate and a manual mechanism. Demonstration content: Demonstrate the working principle of a single-phase AC generator; electric-phase DC generator Great educational toy, it can cultivate children's interest in physics, more intuitive and easy to understand Good for school teaching tool, learning display, and collectibles, also be a great addition to supplies. Colour:As shown Material:Metal Package Contents: 1 set * Hand crank AC/DC generator Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.