Description: PCB board design is reasonable, no flash, the size is the same as the size of the ID card, you can fit in your pocket. The use of commonly used patch components. The left and right three columns of components are used to practice welding, each column with test points. The middle circular circuit is a water-lighting circuit, which is composed of 4017, NE555, and light-emitting diodes. The back of the circuit is also used, there is a ruler, convenient to measure components. There are PCB wire examples to facilitate PCB design use. Specification: Material: electronic components PCB board size : approx. 81 x 55mm/ 3.19 x 2.17inch Circuit operating voltage: 3-12V Many types of components, are commonly used components, very suitable for training. Welding is a beautiful water light circuit Package Includes: Set of Materials 1 Piece English manual(6 Pack) Note: Please allow 1-3mm error due to manual measurement. Please make sure you do not mind before you bid. Photo color might be a little different from the actual product due to color display of different monitors. Thanks for your understanding and enjoy your shopping moment.