They convert optical signals back into electrical impulses that are used by the receiving end of the fiber optic data, video, or audio link. The most common detector is the semiconductor photodiode, which produces current in response to incident light. The LightBeat™ feature flashes the LED, indicating a powered-on condition and good battery and a timer shuts FiberLert™ Detector off after five minutes of inactivity to extend battery life (2xAAA, included). Rugged design includes a convenient pocket clip and is backed by a two-year warranty. FiberLert is a fast, accurate, and safe non-contact solution for verifying fiber activity, polarity, and connectivity.