DESC: Horizon powered subwoofers feature large front-firing cones and Boston's proprietary Deep Channel Design (DCD) technology. These subwoofer are ideally suited for use in a high-quality 5.1-channel home theater or stereo music system. It is capable of impressive deep bass and high output from remarkably compact enclosures. In addition, they feature BassTrac, a proprietary Boston-design circuit that tracks the input signal to the subwoofer and prevents its amplifier from being drive to audible distortion.