The SB16-Ultra is a sealed box powered subwoofer with a massive 16-inch Ultra driver featuring an 8-inch edge wound voice coil, a stunningly powerful Sledge amplifier with fully discrete MOSFET output and an innovative subwoofer control and DSP smartphone app with custom presets for precision tuning. Running dual subwoofers smooths bass response throughout the listening area, enhances low frequency output and depth, reduces localization and provides other acoustic benefits over a single subwoofer.