XD300/1 - JL Audio Monoblock Class D Series Subwoofer Amplifier XD300/1 - JL Audio Monoblock Class D Series Subwoofer Amp Unregulated MOSFET switching type power supply NexD Ultra-High Speed Class D topology LED power (green) and protect (red/yellow) indicators Dimensions: 6-7/8"L x 7-1/16"W x 2-1/16"H