SNS can be divided into active protection system and passive protection system. Made with steel wire ropes as major components, the covering protection type is called active system while the holding protection type is called passive system. So, SNS has two basic types of flexible security system technology and products to prevent geological disasters of various slopes and avalanche slope, bank erosion, blasting stone fly, falling objects and other hazards. The passive SNS shielding system is also called stone blocking mesh, made by flexible steel wire rope netting installed in the slopes to stop the falling rocks. It can also be installed in the mud-rock flow area to form the flexible fencing dam to stop the huge solid pellets in the flow. This product is widely used in the railway, highway, the mine, the water and electricity project, the tourist site, the river course and in the municipal engineering. SNS is one kind of new technical product completely changed the traditional ideas of slope protection. This product has incomparable advantages compared with other similar products. When works as products withstanding huge impulse, it can avoid the damage may caused by the partial centralism stress, with the lengthened response time; increased mesh point surface; at the same time, it receives the partial stress with the whole. The SNS product is suitable for any complex terrain, while maintaining the primitive landform. SNS product has mesh opening allowing good vision, convenient for planting trees and grasses and good for the environmental protection. It is simple for installation to save time. The product has standard components that do not need site further processing. Simple machine, less labor and a small quantity of earth and stone foundation are needed for the building block system installation quickly and easily. It does not need to excavate massively, does not need the massive material, does not disturb the neighboring buildings normal operation and other construction function, hence to avoid the heavy economic loss caused by ???the disturbance???.