Re Audio Xxx18d2 18" 2,000 Watt Rms Rated (4000w Peak) Dual Voice Coil 2 Ohm Competition Car Subwoofer Electrical Q Value -Qes: 0.68 Equivalent Compliance -Vas: 482.0 liters Effective Piston Area -Sd: 1210 cm^2 Sealed Enclosure: 3.3 - 4 Basket Depth - 9.75"