Features: Adopts thick copper bar to effectively enhance working efficiency and work for long time. Integrated design and fine workmanship ensure great heat radiation effect and stable performance. Dual spring on the handle, so that each welding pen can expand and contract independently. With built-in limit switch, support one hand operation, do not need foot pedal. With comfortable grip, it supports long time use without fatigue, reliable and effort-saving. Suitable for 18650 battery spot welding machine.