Max Power Rating (Watts): 140 RMS Power Rating (Watts): 40 Compliance (Cms): 767.95 Cone Area (Sd): 8 D.C. Coil Resistance (Re): 3.6 Electrical Q (Qes): 1.047 Force Factor (Bl): 3.246 Free Air Resonance (Fs): 67 Frequency Response: 72Hz - 21kHz Impedance (Nominal): 4 Mechanical Excursion (mm): 9 Mechanical Q (Qms): 2.592 Sensitivity (dB) (1W/1M): 87 Total Loudspeaker Q (Qts): 0.746 Magnet Structure (Oz): 8