Effective Piston Area (Sd): 0.0745 sq m. Efficiency (1W/1M): 88.595dB REVC: 3.5 Ohm BL: 15.4517TM VAS: 1.6456 cu ft. Nominal Impedance: 4 Ohm Power Handling: 1500 Max Includes One Subwoofer Earthquake’s next generation of TremorX subwoofers is ready to get louder and lower than any other subwoofer in its category. The new TremorX’s are built with TCT technology which allows the driver to play louder longer by keeping the voice coil running cool at all times. These bad boys also have stitched leads, reinforced dust cap construction for linear movement, and bigger, more effective magnets with added cooling devices to increase efficiency even more. The TremorX subwoofers have no equal and are ready to prove it. 15" 1500 Watt High Performance Subwoofer New design High SPL Stitched tensile leads Spring loaded terminals TCT (Turbine Cooled Technology) V-12 aluminum voice coil Thick high density magnet Pressed pulp fiber cone High roll surround Package of 1 Subwoofer