M500/3 - JL Audio 3-Channel Class D M-Series Marine Amplifier 3-Channel Class D M-Series Marine Amplifier Unregulated MOSFET switching type power supply NexD Class D Technology reduces distortion and delivers superior efficiency Fully variable 12dB/octave filters with filter frequency selection controls Dimensions: 10-1/4"L x 7-1/16"W x 2-1/16"H