The Skar Audio ZVX-8 D4 is an SPL grade 8-inch car subwoofer with a Dual 4 Ohm voice coil configuration. This ZVX-8 was engineered to get loud, featuring a 2.5-inch high temperature voice coil, as well as an extremely powerful 156oz triple stack ferrite motor. Combine those features with its competition grade paper cone and high roll foam stitched surround, and this 8-inch driver will deliver the performance and reliability expected out of a competition grade subwoofer. Dual 4 Ohm voice coil configuration. RMS Power: 900 Watts, Fs: 40.0 Hz.