MODEL:PA1801 SIZE:18" Nominal impedance:4 Ohm Rated capacity:300 Watts RMS sensitivity (1M 1W): 98 db Actual periodicity30Hz~ 2000Hz Min. sympathetic vibration periodicity :30 Hz Drum membrane material: PAPER CONE + CLOTH EDGE Voice coil diameter:3 IN (75.5MM) Voice coil material :KAPTON Magnetism coefficient(BL):13.445TM Mechanism Q value (Qms): 5.066 Electric Q value (Qes): 0.394 Total Q value (Qts): 0.364 Equivalent voice volume (Vas): 793.96 Ltr Magnet weight:2214.6g(78 OZ)