Specification:  Material: Metal.  Size: Approx. 105*83.2*28.8mm.  Cell: 2 * High-speed cell (included).  Output Voltage: 4.2V max.  Output Current: 639A max.     Feature:  Portable spot welding machine, with quick release welding pen.  The integrated solder pen uses gold Plate terminal, with fine conductivity and low contact resistance.  Adopts a micro USB charging interface for easy charging.  Built-in high-speed battery 2, with fine charge and discharge properties.  Fine workmanship and good performance.  Easy to use.  Long service life.     Use Instructions:  1. Please extend pressing for 3 seconds. When the buzzer rings, that is turn on/off.  2. Short press the button. If the buzzer rings, that is shift position. Press one time, and it can add 1 gear. 1-9 cycles, and the 9th gear is the strongest welding strength.  3. After placing the welding pen, the buzzer rings. Waiting for about 0.5 seconds to trigger welding.  4. When charging, the power indicator flashes. When all 4 lights are on to indicate that it is fully charged. Welding can be performed while charging.     Package included:  1 x Spot Welding Machine.     Note:  1. Please allow 1-2cm error due to manual measurement.  2. The colors may have different as the difference display, please understand.