The RS820-2102 from Oelabs is a Optical Time Domain Reflectometer (OTDR) with Event Dead Zone 1 m, Attenuation Dead Zone 10 m, Optical Wavelength 1310 to 1550 nm, Dynamic Range 38 to 40 dB, Pulse Width 5 to 20480 ns. More details for RS820-2102 can be seen below.