[SMD/SMT Components Soldering Practice Board]: Input voltage: DC5V. The positive pole is connected to +, and the negative pole is connected to -. After the SMD components are soldered, power on to form a running water lamp to detect the effect of the soldering. [Before Soldering]: Some SMD components are relatively small, be careful not to lose them. The side of the diode with the green dot is the negative electrode. This electronic soldering kit is not a finished product, it need to be soldered by yourself. [Great Soldering Science Project]: This soldering DIY kit help you understand the basics of working with printed circuit boards and become familiar with a variety of electronic components, and practice soldering skills enjoyably and your kids, or students, or DIYers. [Easy to Assemble]: The connection that was clearly mapped and labeled on the board makes it easy to assemble. And you can refer the marks on PCB board to soldering each component. Precautions for welding:SMD components are relatively small, be careful not to lose. Different batches have different silk screen batch numbers, which does not affect use. Colour:Blue Material:PCB+electronic components Package Contents: 1 x Component Welding Practice Board Set 1 x Battery case 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.