PAIR OF E-15 V.3 D4 - Sundown Audio 15" 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 Box Recommendations: Sealed: 2.5 ft^3 | Ported: 3.25 ft^3 | Displacement: 0.14 ft^3 | Depth: 7 1/4" | Outside Diameter: 15 1/8" | Cut-Out: 13 7/8" | Recommended Tuning: 32hz | Recommended Port Area: 52 in^2