Dynamic Balance® Woofer Design Polk perfected the method of analyzing a speaker's microscopic behavior with laser Interferometry. With that information in hand, Polk engineers select the ideal combination of materials, geometry and construction techniques to literally “tune out” unwanted resonance. The result is a subwoofer that delivers pure, distortion free deep bass.Klippel Optimized Long Throw Woofer Using a state-of-the-art Klippel Distortion Analyzer, Polk engineers optimized the woofer's motor structure, voice coil alignment and suspension for longer excursion and greater linearity bringing you the best possible performance even at the most extreme listening levels.Slot Load Venting improves bass response. The wide, long slotted vent dramatically lessens turbulence, noise and distortion, pouring out a tidal wave of precise, thunderous bass!Rock-solid MDF construction (including a 1 inch thick front baffle) suppresses enclosure panel resonance for distortion-free, accurate response. Polk subs sound better because they're built better.