NK4000 series OTDR adopts 4.3-inch capacitive touch screen.It integrates 12 functions,such as auto OTDR,expert OTDR,event map,OPM,RJ45 cable tracker,and "computer level"file management to meet various testrequirements in different occasions.OTDR has a maximum dynamic range of 26dB,8G memory,and can store more than 200,000 curves;itis equipped with 4000mAh high-density polymer lithium battery,intelligent power saving management,measuring time of more than 8 hours,and supporting power supply and charging of the power bank. NK4000 series are used to measure the length,loss,connec- tion quality and other parameters of optical fiber.It is widely used in FTTX,secondary backbone network engineering construction,maintenance and emergency repair test,and production measurementof optical fiberand cable.