1.  Effectively shrink size of incision surgery, maximum open wounds, meanwhile view of surgery can be fully exposed;

2.  Equal wounds tension reduce tissue injury;

3.  Viscera can be pulled out to be operated;

4.  Original design, multiple models, can satisfy every demand of different surgeries;

5.  Smaller incision, smaller incision better concrescence;

6.  Prevention of II or III wounds or incision infection, prevention of tissue burns censed by mistake