A Continuity Tester enables you to easily verify light throughput (continuity) of a fiber optic link. The device also enables you to identify multiple fibers at an interconnect location. To use the FIS Continuity Tester, simply attach your connector to the adapter and push the on/off button. The LED transmits red light down the fiber, providing visual identification at the fiber's far end. Operates with two "AA" size batteries (provided). Contained in durable hard rubber housing, the compact unit stores easily in your toolbox.