1Thick Brass Rod: This 18650 battery spot welding pen is made of thick brass rod, which has higher over current, no resistance to heat, and more stable spot welding power. It is suitable for long time work, improve efficiency. 2Double Springs: There are double springs in the handle that can be retracted, each welding pen is independently retractable, and the strength is moderately controlled. 3Eccentric Welding Needles: Using eccentric welding needles, it is possible to weld a very narrow nickel sheet, and at the same time, both welding pins are kept perpendicular to the nickel sheet, which increases the contact current. The spot welding pen comes standard with a pair of concentric ball needles, which works well. 4One Handed Operation: Built in stroke switch, it can be operated with one hand. It will not be fatigued due to long strokes and heavy spot welding handles during long term work. It is very suitable for mass production. 5Easy to Use: It will not happen that the ordinary integrated spot welding pen cannot achieve the pressure balance of the two welding pins, which will cause the welding to be weak and sparks.