Nominal diameter: 305 mm/12in Power rating: 450watt-900watt Nominal impedance: 8 Ohm Sensitivity: 97dB Frequency range :55-3500Hz Chassis type: Cast alumium Magnet type : Neodymium Magnet Size: 74x15x10mm Magnet weight: 0.32 kg/11.3oz Voice coil diameter: 75.5 mm/3in Coil material: CCA-W Number of layers: 2 (Inside/Outside) Former material: Glass fiber Cone material: Paper Surround material: Cloth Spider: Single X-max: 5 mm/0.9 in Gap depth: 9 mm/0.35 in Voice coil winding width: 16.5 mm/0.64 in Net Weight: 3.97kg/pcs Gross Weight: 4.43kg/pcs Packing Dimension: 333216.5cm