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.Kappa subwoofer cones incorporate glass-fibers for exceptional accuracy and detail. Inherently non-resonant the glass-fiber cones eliminates distortion so your music—and nothing but your music—comes through loud and clear.