The 4115HT is a powered full-range, two-way system designed for a wide variety of speech and music applications, such as clubs, churches, or concert settings. The 4000 Series features our exclusive “OPC” system (patent pending) with LED indicators mounted on the baffle. A green LED which lights when there is signal present - and a red LED which lights when the OPC (overload protection circuitry) senses an overload condition in the HF driver. The OPC turns down (-10dB) the HF driver temporarily, and the red LED flashes, indicating an overload. When the HF driver cools, or the power is decreased, the OPC automatically resets itself and signal is restored to the HF driver.