The21 SUB WF PRO PASSIVE SEALED is an application-specific version of our highly regarded The21 SUB PRO PASSIVE SEALED. The WF designation in the model name stands for WaveForming. Use of Trinnov’s WaveForming technology determines not only the number of subwoofers on both the front and rear walls, but their precise locations on each wall, as well. Taking into consideration the locations of the front wall screen channel loudspeakers and the rear wall loudspeakers, the size and shape of the subwoofer cabinets is critical to ensure both location flexibility and realized performance. When customers experience the unparalleled output and uncolored sound of The21 SUB WF PRO PS, the measured test results we publish translate perfectly to realized performance. ASCENDO’s policy is to be completely transparent and publish measurements done by independently certified third-party labs to provide factual data, thereby enabling informed, educated decisions. The The21 SUB WF PRO PS subwoofer is so far above and beyond the competition in every aspect; refined musicality, tightness, and output levels suitable for a 21"" driver. It is also engineered to operate perfectly in sync (in phase) with our Infrasonic subwoofers; The24 PRO, The32 PRO, The50 PRO, The80 PRO when there is a desire to reproduce movie content below 20Hz with the same authority, precision, and musicality.