SD-3 10 D2 - Sundown Audio 10" 500W RMS Dual 2-Ohm SD Series Subwoofer SD-3 10 D2 - Sundown Audio 10" 500W RMS Dual 2-Ohm SD Series Subwoofer Power Rating: 500W RMS | Voice Coil: Dual 2-Ohm Specifications: DC Resistance (Re): 3.72  | Resonance Frequency (Fs): 25.7 Hz | Equivalent Volume (Vas): 35.5 L | Electrical Q Factor (Qes): 0.49 | Mechanical Q Factor (Qms): 3.12 | Total Q Factor (Qts): 0.42 | Force Factor (BL): 14.28 NA | Moving Mass (incl. Air Load) (Mms): 165 g | Suspension Compliance (Cms): 230 m/N | Sensitivity: 82.9 dB 1w / 1m Box Recommendations: Sealed Enclosure Suggestion: 0.5 cu. ft. | Ported Enclosure Suggestion: Not Recommended | Displacement: 0.11 cu. ft. | Depth: 4.48 in |Outside Diameter: 10.5 in | Cutout: 9.25 in | Recommended Tuning: 32 Hz | Recommended Port Area: 16 sq. in.