VTX series dual 18" subwoofers employ two 2269H 18" transducers featuring Differential Drive technology with two voice coils, two neodymium magnets and extremely high peak-to peak excursion capabilities to deliver extended very low frequency performance. The VTX G28 is ground stackable only with a practical form factor for convenient stacking and additional enclosure volume plus port tuning that delivers true sub performance down to 22 Hz @ -10 dB.