Fiber Optic Light Source, Application Tests And Maintains Fiber Optic Cables, For Use With 3LW06, Output Wavelength 850 Nanometers And 1300 Nanometers, Output Power -20 Dbm, Agency Compliance IEC 1010-1 and IEC 825-1, Meets/Exceeds All Requirements For Class 1 LED Products, Includes 9 V Battery And Instructions. A variety of light sources allow you to test different cable lengths. One year warranty.