Rockville RGHR45 is here to bring you into the modern era of marine entertainment. This 4-zone marine gauge hole receiver combines the latest in audio technology with rugged construction designed to stand up to the elements. This receiver fits into a standard gauge hole (tachometer) opening, making it easy to install on your boat. The built-in 4-channel amplifier provides plenty of power to drive your speakers, and the separate subwoofer output ensures that you'll have plenty of bass to enjoy your music.