Since the end of the 1970s, China's aluminum alloy doors and windows, curtain wall industry began to take off, the promotion and application of aluminum alloy glass curtain wall in the building, from scratch, from imitation to self-development, from the construction of small projects to contracting Large-scale engineering projects, from the production of low-end products to the production of high-tech products, from the construction of low-rise building doors and windows to the construction of high-rise glass curtain wall, from the processing of simple low-end profiles to the extrusion of high-profile profiles, from import to development The external contracting project, aluminum alloy doors and windows and glass curtain wall have been rapidly developed. By the 1990s, the emergence of new building materials promoted the further development of building curtain walls. A new type of building curtain wall appeared in various parts of the country, namely metal curtain wall. The so-called metal curtain wall refers to the building curtain wall whose curtain wall panel material is metal sheet. Nbr O-Rings,Rubber Oil Seal,Window Rubber Seal Xlong Seal Co., Ltd. , http://www.xmseals.com