Specifications: Nominal Diameter: 18 inch / 457 mm Rated Impedance: 8 ohm Program Power (watt): 2000 W Power handling capacity: 1000 W Sensitivity: 97.5 dB Frequency range: 25 - 1000 Hz Effective piston diameter: 395 mm / 15.55 inch Max. Excursion Before Damage: 50 mm / 1.97 inch Minimum Impedance (ohm): 6.5 ohm Voice Coil Diameter: 4.0 inch / 102 mm Voice Coil Winding Material: Copper Voice Coil Length: 25 mm / 0.98 inch Number of layers: 2 Kind of layers: inside/outside Top Plate Thickness: 15 mm / 0.59 inch Cone Design: Straight Surround Material: Polycotton Surround Design: Triple roll Magnets: Ceramic Dual-force air ventilation: Yes Spider: Dual with silicon based damping control