Diameter 165 mm / 6.50′′ Impedance 4 Ohms Efficiency 89 dB Frequency Response 40 Hz – 25 kHz Tweeter GZUT 28SQ Outer diameter 54 mm / 2.13′′ Midrange Speaker GZUM 55SQ High performance midwoofer GZUK 165SQ Speaker Diameter 165 mm / 6.5′′ Mounting diameter 144 mm / 5.67′′ Mounting depth 63 mm / 2.48′′ Crossover Variable 3-way Crossover frequency 450 / 4500 Hz