IDQ 8D4 V.4 - Image Dynamics 8" 500W RMS Dual 4-Ohm IDQ V.4 Series Subwoofer IDQ 8D4 V.4 - Image Dynamics 8" 500W RMS Dual 4-Ohm IDQ V.4 Series Subwoofer RMS Power: 50-500W Outside Diameter: 212mm (8.35") Cut-out Diameter: 184.40mm (7.26") Mounting Depth: 125.75mm (4.95")