Lightning Audio L3-D412 LA-Three 12-Inch 4 OHM Dual Voice Coil Subwoofer, Set of 1 L3 12" 4-Ohm Dual Voice Coil Subwoofer High modulus closed conical polypropylene cone and dust cap assembly geometry Tear and fatigue resistant poly-cotton spider High density compressed half-roll sealed poly-foam surround High temp voice coil with spun-laced Nomex insulating reinforcement collar