The Noratel FR120B-400230 is a 120-volt, 400-watt fiber optic light source that provides continuous and stable output power suitable for testing and measuring optical fiber applications. It can be used with Optical Time Domain Reflectometers (OTDRs) and Directional Couplers to accurately measure the optical power of optical fibers during installation and maintenance of fiber optic networks. It has dual outputs that can be used to measure optical loss and power at two different wavelengths. It is equipped with an LCD display which shows the output power level and wavelength selection. The wavelength range of this device is from 780nm to 1650nm. It is encased in a rugged and compact enclosure, making it suitable for use in both indoor and outdoor environments.