Order by 2PM weekdays for Same Day Dispatch. Ground Zero Hydrogen GZHW 20XSPL-D1 Sub 20cm 8 Inch SPL Subwoofer 700w RMS. 20 cm / 8? High quality SPL subwoofer. 8? High quality SPL subwoofer with alumiunum cast basket and reinforced paper cone. 8? High quality SPL subwoofer. Long stroke compound surround. Solid aluminum cast basket. 63 mm / 2.5? Copper voice coil. IMPP dust cap with 3D structure logo. Model High-Quality SPL subwoofer. Diameter 20 cm / 8? Impedance 2x 1 Ohms. Power recommendation 50 – 1500 Watts. Voice coil 63 mm / 2.5? Copper. Excursion (Xmax) 40 mm / 1.57? Mounting Ø 187 mm / 7.36? Mounting depth 145 mm / 5.71? Resonance frequency (Fs) 38.3 Hz. Overall quality (Qts) 0.381. Air volume (Vas) 4.77 L / 0.17 cu.