The Earthquake Sound Subzero monster bass drivers rule in speed, sound quality, and SPL. Armed with a U.S. made massive 3.25" aluminum voice coil former with a flat wire wrapped edge wound style, it easily uses 2000 Watts RMS. With a 3.5" tall winding height on the 15" model, this subwoofer has an astounding 4 inches of peak to peak travel, with the winding in the magnetic gap at all points of travel. The Subzero 15 also boasts TCT (Turbine Cooled Transducer) coil and pole cooling technology, plus the PSP Terminal block that allows stereo and mono impedance changes just by flipping fuses. With the Subzero 15, you have the perfect combination of looks, performance, reliability, longevity, and ease of installation.