CELESTION FTR184080FD FTR Series 18-Inch 1000-Watt Subwoofer Nominal diameter 457 mm/18 in Power rating 1000W rms Nominal impedance 8 Sensitivity 297 dB Frequency range 30-2500 Hz Voice coil diameter 100 mm/4 in Chassis typecast Aluminum Magnet type Ferrite Magnet weight 3.1 kg/110 oz. Coil material Round copper Former material Glass Fibercon material Glass loaded paper with weather-resistant impregnation