The LOR-220 POF from Luciol Instruments is a Optical Time Domain Reflectometer (OTDR) with Attenuation Dead Zone <1 mm to 40 cm, Optical Wavelength 520 to 650 nm, Dynamic Range >20 dB, Pulse Width 1 ns, Distance Range 0.5 km. More details for LOR-220 POF can be seen below.