The MT9085B-055 from Anritsu Corporation is a Optical Time Domain Reflectometer (OTDR) with Optical Wavelength 1310 to 1650 nm, Dynamic Range 35 to 42 dB, Pulse Width 3 to 20000 ns, Distance Range 0.5 to 300 km (SM), 0.5 to 100 km (MM), DC Voltage 12 VDC. More details for MT9085B-055 can be seen below.