M400/4 - JL Audio 4-Channel 400 Watt Marine Amplifier M400/4 - JL Audio 4-Channel 400 Watt Marine Amplifier NexD technology features unsurpassed efficiency Pulse Width Modulated MOSFET power supply Remote bass level input (JL Audio HD-RLC remote level control sold separately) Dimensions: 8-1/2"L x 7-1/8"W x 2-1/16"H