Sundown Audio E-10 V.3 D4 10" 500W RMS Dual 4-Ohm EV.3 Series Subwoofer RMS Power = 500-watts | Xmax = 14mm one-way by 70% BL | Vented magnetic gap Vented pole piece with optimized geometry | Black Aluminum 2.5 voice coil former for superior heat dissipation | High Temperature 4-Layer copper voice coil wire Spring Loaded Terminals | Stitched-On Mini-XL Tinsel Leads to prevent fatigue and failure Specifications: DC Resistance (Re): 6.1  | Resonance Frequency (Fs): 33.5 Hz | Equivalent Volume (Vas): 18.8 L | Electrical Q Factor (Qes): 0.43 | Mechanical Q Factor (Qms): 4.39 | Total Q Factor (Qts):0.39 | Force Factor (BL): 23.5 NA | Moving Mass (incl. Air Load) (Mms): 183.7 g | Suspension Compliance (Cms): 0.12 mm/N | Sensitivity: 84 dB 1w / 1m Box Recommendations: Sealed: 0.5 cu ft | Ported: 1.0 cu ft | Displacement: 0.11 ft^3 | Cutout Diameter: 8-7/8" | Outside Diameter: 10" | Depth: 5 5/8" | Recommended Tuning: 32hz | Recommended Port Area: 16 in^2