Diameter 165 mm / 6.50″ Power Handling (RMS/max.) 120 / 180 Watts Impedance 4 Ohms Efficiency 87 dB Frequency Response 40 Hz – 3500 Hz Voice Coil 50 mm / 2″ copper Membran Layout anodized aluminum Magnet material Neodymium Mounting Ø 144 mm / 5.67″ Mounting Depth 63 mm / 2.48″ Resonance Frequency (Fs) 54.6 Hz.