Features: brand new and high quality The PCB board has a reasonable design and can be put in a pocket. All commonly used SMD components are used. The left and right 3 columns of components are used to practice soldering, and each column has test points. The circular circuit in the middle is the water lamp circuit, which is composed of 4017, NE555, and light-emitting diodes. It can work after the welding is correct. The back of the circuit is also used, and there is a ruler, which is convenient for measuring components. There are examples of PCB wires to facilitate PCB design and use. The working voltage of the circuit is 3-12V. Specifications: Material;ABS Size:Approx.8.56x5.4x0.2cm/3.37x2.13x0.08in Net Weight:25g Note: Please allow 1mm errors due to manual measurement. Due to the difference between different monitors, the picture may not reflect the actual color of the item. Package includes: 1Set Soldering Practice Board