Usage:using the fiber connector imputs the red light into the fiber,using for the fiber comparision of many fiber cable.It can detect the fiber fault that OTDR can not and the high wastage junction causing by the bending.Like the core wire of fiber patch cord,pig tail,Fiber junction box.Or Bare fiber and so on.Fiber identification distance is up to 5 km.it is the instruments which each maintenance technician must be equipped.