Waterproof Marine Audio Syst The MS-551 Subwoofer with Amp is optimized for marine applications. It's small size enables it to be easily mounted below seats, under the gunwale area, behind the instrument panel, or any convenient location. It features a self contained bass unit requiring no cutting of panels or holes in the boat interior. It produces solid, deep bass boat's audio system. 520 McCormick Dr. • Glen Burnie, MD 21061 • (410)761-4000