NSK (Shenzhen) Control Technology Co., Ltd is a China Shenzhen based product development and manufacturing company. In the past five years, we have been focusing on audio and video intercom system. by the end of 2008, CX System, NCX System, TW System, PBX System and DWL System had been designed, tested, produced and marketed in different regions around 60 counriries of the word and are exploring more