?NSK?, formally named NSK(Shenzhen) Control Technology Co.,Ltd, is a Shenzhen basedChinese manufacturing company with R&D and marketing departments. We have been focusing onVIDEO DOORPHONE and VIDEO ENTRY SYSTEMS for last 7 years, and following systems hadbeen launched and marketed successfully:1. CX system: Four wire, ?Star? type connection;2. DCX system: Four wire, ?Distributor Bus? connection?3. NTW system: Two wire, ?Repeater Bus? connection;4. PBX system: PBX switch + Video distributor Bus connection;5. DWL system: Digital wireless ,2.4G;6. IP system: IP routing.In the 2-3 years, we will eventually launch total security system based and home automation systembased on RSA85,CAN bus,TCP/IP, 3G,?Zigbee and SIP technologies.