Powered subwoofer with 800 watts maximum power, heavy duty castor wheels and pole mount. Limit indicator will blink on occasion when built-in limiter is active. Signal indicator will glow when when there is signal received to full range input. Subwoofer gain control knob is used to regulate output level of sub¬woofer. Use this to set balance between speakers and subwoofers. Protect indicator will begin to glow when subwoofer goes into protect mode. Protect mode prevents subwoofer amplifiers from getting to hot. When sub¬woofer goes into protect mode all output will stop. This is to protect subwoofer and any speakers connected to subwoofer.