SSI™ (Selectable Smart Impedance) Most car audio system designs call for 2- or 4-ohm impedance. Kappa Series subwoofers put the choice in your hands. A proprietary HARMAN technology, SSI lets you reconfigure your system by simply flipping a switch. Aero-cooled voice coil The Kappa Series voice coil employs a two-sided, ducted airflow design that cools the voice coil, increases power handling and improves reliability. This aero-cooling design is unique among aftermarket subwoofers. Acoustically damped glass-fiber cone Kappa subwoofer cones incorporate glass-fibers for exceptional accuracy and detail. Inherently nonresonant, the glass-fiber cones eliminates distortion so your music—and nothing but your music— comes through loud and clear. Premium screw-down terminals Power is the lifeblood of any subwoofer. The terminals on the Kappa subwoofers accommodate up to 8-guage wire (8.37mm 2 cross section), which transfers low-resistance, low-loss power to the woofer, even over long wire runs.