Earthquake Sound DBXi-15D 15-inch Subwoofer with Dual 4-ohm Voice Coil, 2000 Watts Super Wide Edge surround is 1.25" high multi-layer foam pressed and laminated, allowing cone movement well over 3" without deformation Hot-forged single piece T-YOKE permits a clear flow of magnetic flux, increasing efficiency Turbo forced-air cooling system Progressive design double spiders allows long excursion with perfect linear motion Highest quality tensile leads for a longer life