The Series II enclosure delivers enhanced efficiency and higher output of a vented enclosure, without the distracting noise or chuffing generated by a port. The patented Slipstream port dramatically reduces port noise at high sound pressure levels by minimizing airflow turbulence. With high-roll surrounds, proprietary cone design, and long-excursion, the Series II enclosure delivers deep, powerful bass with greater accuracy than conventional ported boxes. The exclusive SSI (Smart Selectable Impedance) switch allows you to choose between 2- or 4-ohm impedance for maximum configuration flexibility. It’s everything you want in a compact, easily installed enclosure.