Ground Zero GZUW 8SQ-D2

20 cm / 8″ SQ Subwoofer, 300 WRMS Rec. amplifier power 2-400 Watts ( rms ) 2 x 2 ohm 50 mm / 2″ copper voice coil Reinforced paper cone Audiophile POLYCOT spider Fs 56.9 Hz Qms 11.92 Qes 0.74 Qts 0.69 Vas 4.8L Le 1.57 mH Mms 92.9 gr Bl 13.55 Xmax 20 mm Effiency 83 dB Outer diameter 215mm Mounting cut out 181mm Mounting depth 108mm.