OWL WS-SDst Wavesource Single Mode Light Source for Fiber is a professional quality fiber optic light source that provides high output and stability at an economic price. The OWL WS-SDst features temperature-compensated outputs, an intuitively designed four-button interface, clear LED indicators, and battery indicator to ensure maintenance of proper output. Additionally the OWL WS-SDst is NIST calibrated and can be combined with an OWL WaveTester for automatic wavelength switching, saving greatly on test time.