Its main operating principle can be described as following: it accumulates energy to a degree and the strike head of the product starts working all of a sudden, and the nut is tightened / lossened in an instant. Thus it produces a large torsion moment without any counterforce. Besides, it is fast to load / dismantle screw nut with our product. It takes less than 10 seconds to load / distmantle a screw nut. What we want to specially point out is that: compared with products of same kind in market, our product adopts a high strength clutch device, which prevetnts the electric machinery from being locked and protects it efficientcy as far as possible.The adoption of such high strength clutch device reduces mechanical wear remarkably.So our products own a longer sevice life and a stable and reliable performance.This technology gains a national invention patent (patent number: ZL 03255638.1 ZL 200530044271.9, patent application no.: 200530034526.3) Specifications: 1) Voltage: DC 12V 2) Output torsion: 200N.m 3) Output square shaft: 1/2" 4) Load current: