The 4100 Series from Viavi Solutions Inc. is a Optical Time Domain Reflectometer (OTDR) with Event Dead Zone 0.65 m, Attenuation Dead Zone 2.5 m, Optical Wavelength 1310 to 1650 nm, Dynamic Range 36 to 45 dB, Pulse Width 3 ns to 20 µs. More details for 4100 Series can be seen below.