Ⅰ. Different layers with different density. To arrange these layers reasonably and exactly, the screening effect will become more and better. Ⅱ.High strength frame, multi-ribs and the mesh cloth with moderate tension , from one reliable combination , which can increase screen’s acceptable flow , the intensity and the lifetime Ⅲ.The wedge-shaped fastening device, can make the erection of screens more handily and quickly Ⅳ.The mesh divided into many independent small units by grids of the backing plate ,can prevent rips or tears from spreading overmuch. Accessory prepared rubber stoppers can be used to repair damage. By doing so, the operator can cut down the stop time and reduce the cost.