The FM8513 from Tektronix is a Optical Time Domain Reflectometer (OTDR) with Event Dead Zone 0.2 to 3 m, Attenuation Dead Zone 2.5 to 14 m, Optical Wavelength 850 to 1300 nm, Dynamic Range 26 to 26.5 dB, DC Voltage 10 to 16 VDC. More details for FM8513 can be seen below.