Assembled Mono Speaker Protection Circuit 12Vdc Supply Electronic Circuit Board : FA649 Technical information: Need Power Supply 12Vdc Current consume 30mA. 1 x Relay 12V/10A to connect between speakers and Mon amplifier. LED indicator. Pot to adjust delay time to connect output of amplifier to the speakers. (1-5second) after turn on amplifier. Including the schematic , the instruction how to setup. PCB size 2.32 inch x 1.34 inch.