FWD1206 Nominal Diameter: 123 Impedance: 4 or 8© Frequency Range: 50Hz-2KHz Power( RMS) : 600W Sensitivity: 95dB/ W/ m FWD1506 Nominal Diameter: 153 Impedance: 4 or 8© Frequency Range: 30Hz-2.5KHz Power( RMS) : 600W Sensitivity: 97dB/ W/ m FWD1806 Nominal Diameter: 183 Impedance: 4 or 8© Frequency Range: 34Hz-3KHz Power( RMS) : 600W Sensitivity: 98dB/ W/ m