SA-8 V.3 D2 - Sundown Audio 8" 500W RMS Dual 2-Ohm SA Series Subwoofer SA-8 V.3 D2 - Sundown Audio 8" 500W RMS Dual 2-Ohm SA Series Subwoofer Specifications: DC Resistance (Re): 3.36  | Resonance Frequency (Fs): 38.29 Hz | Equivalent Volume (Vas): 6.88 L | Electrical Q Factor (Qes): 0.324 | Mechanical Q Factor (Qms): 6.310 | Total Q Factor (Qts): 0.309 | Force Factor (BL): 18.94 NA | Moving Mass (incl. Air Load) (Mms): 144 g | Suspension Compliance (Cms): 120 m/N | Sensitivity: 82.79 dB 1w / 1m Box Recommendations: Sealed Enclosure Suggestion: Not Recommended | Ported Enclosure Suggestion: 0.5 - 0.75 cu. ft. @ 35 Hz | Displacement: 0.08 cu. ft. | Depth: 6.625 in |Outside Diameter: 8.375 in | Cutout: 7.375 in