The T339 Optical Power Meter series includes models T339-01B, T339-02 and the T339C. All units are designed to measure optical power of LEDs or laser diodes and work with either singlemode or multimode fibers. The test set is housed in a strong, lightweight metal case, built for long life under severe field operating conditions. Measurements are made by mating the system connector or fiber to be tested to the RECEIVE port of the T339 Optical Power Meter. Interfacing problems have been eliminated by the use of universal adapters. The adapters permit direct connection of a variety of the commonly used connectors of several manufacturers. Bare fiber adapters are also available. The T339 Optical Power Meter is powered by two standard 9 volt batteries. An “Auto Off” feature extends the useful battery which is approximately 50 hours of continuous operation. The T339 comes equipped with a cover designed to store additional adapter caps and a carry-strap.