JL Audio 15W0v2-4 W0v2 Series 15 inch 500 Watts Car Subwoofer DMA Optimized Motor System Highly optimized motor system delivers linear motor force over a wide range of excursion and power levels to reduce distortion. Elevated Frame-Cooling (U.S. Patent #6,219,431) Creates a pathway for high-velocity air to flow directly across the top-plate and onto the voice coil. Insanely Great Bass in Small Enclosures! For maximum application flexibility, W0v2's are designed for use in compact sealed or medium-size ported enclosures. Free Air Resonance (Fs): 24.43 Hz Electrical Q (Qes): 0.508