Sundown Audio SD-3 8 D2 8" 300W RMS Dual 4-Ohm SD Series Subwoofer Power Handling: RMS Power = 300-watts Voice Coil Configuration: Dual 4-Ohm Under-Hung low distortion motor topology Solid pole piece with chamfered edges Specifications: DC Resistance (Re): 6.1 Ω Resonance Frequency (Fs): 46.4 Hz Equivalent Volume (Vas): 5.8 L Electrical Q Factor (Qes): 0.67 Mechanical Q Factor (Qms): 3.97 Total Q Factor (Qts): 0.57 Force Factor (BL): 16.4 NA Moving Mass (incl. Air Load) (Mms): 100.7 g Suspension Compliance (Cms): 0.12 mm/N Sensitivity: 81.2 dB 1w / 1m Box Recommendations: Sealed Enclosure Suggestion: 0.4 cu. ft. Ported Enclosure Suggestion: Not Recommended Displacement: 0.10 cu. ft. Depth: 4.75 in Outside Diameter: 8.375 in Cutout: 7.375 in Recommended Tuning: 32 Hz Recommended Port Area: 8 - 12 sq. in