The analog assembly line consists of: power supply circuit, air shower circuit, short circuit detection circuit, induction circuit, vibration detection circuit, metal detection circuit, infrared detection circuit, single-chip circuit, etc. This kit uses steel balls to objects, and the rolling of the steel balls along the track in the figure below represents the assembly line operation of the objects. Note: It's diy kits. Need to solder by yourself. There are differences in components between different batches, which does not affect the use Colour: Blue Material: PCB+Components Package Contents: 1 x DIY kit 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.