What is it? A VLF subwoofer module designed to integrate with Bose's RoomMatch progressive directivity array systems. Details The RMS218 subwoofer features dual Bose LF18 18" high-excursion, neodymium-magnet transducers with 4.5" voice coils said to offer increased power handling and reduced power compression. The V-baffle design features a large centre port for reduced airflow turbulence and distortion, while also minimising enclosure width to allow integration with all RoomMatch modules. The RMS218 enclosure is constructed from Baltic-birch plywood finished in a 2-part polyurethane coating resistant to scratches and scuff marks. An optional RMSFLY218 kit allows suspended array applications. The RMS218 VLF-subwoofer module can be used with RoomMatch full-range array modules to form high-impact, 3-way systems. For advanced configurations, the RMS218 VLF subwoofer can be used with RoomMatch RMS215 and full-range modules for 4-way operation. Frequency response for the RMS218 subwoofer is quoted at 30Hz -200Hz (+/- 3dB) with a usable frequency range extending down to 25Hz (-10dB). Long-term continuous power handling is rated at 2.5kW delivering peak SPLs of 141dB. And another thing... Bose also produce the smaller RMS215 dual 15" subwoofer for use with RoomMatch array systems.