SB AUDIENCE ROSSO-18SW800, 470mm Paper Cone Pro Subwoofer 8 OHMFeatures Proprietary cone paper material with silk cotton tree Minimum damping fiber glass voice coil former 4" voice coil with APC (Advanced Polymer Coating) Ribbon voice coil wire for high efficiency Cast aluminium chassis Vented pole piece for reduced compression Cooling device on yoke for increased heat transfer