Very good cosmetic condition. Tested working. Output at the beginning of the test is high. After several minutes, output power is stabilized to a lower value. The peak output is around 19dBm at 1535.5 nm, tested by OSA or power meter (inserting a 10dB calibrated attenuator and extra jumper before OSA) in our lab. It requires an external isolator to get stable EDFA output if there is no isolator within narrow line-width laser signal source. We also add 2nd isolator before OSA to improve the stability and output power a little. We set coherence control in tunable laser source. The output at 1543nm is also around 19dBm approximately. At other wavelengths within C-band, fiber amplifier output typically 1dB lower. Output power is sensitive to connection status in the EDFA output interface at the instrument front panel. We got higher power up to 23dBm once, but it seems we cannot get 23dBm anymore after we change fiber jumper and change the laser source. You need do more research on using this instrument.