Alpine's Halo Series subwoofer enclosures make it easy to add more bass to your system. The pre-loaded R-Series 12" dual voice coil subwoofer provides plenty of bass on its own, but when you want even more, the optional linking kit can connect two together for double the impact. | Alpine | | Halo R2-Series 12" Dual Voice Coil 4-Ohm Loaded Subwoofer Enclosure | Black | Best Buy