Polk Audio DB 124 12-Inch Subwoofer (Single, Black) A single marine-certified subwoofer suitable for use in cars, trucks, boats, and other vehicles 12-inch polypropylene cone woofer with rigid ABS 4-layer Kapton 2-inch diameter voice coil Frequency response: 27 Hz to 200 Hz Mounting cutout diameter of 11-inches, mounting depth of 6.75-inches