Alpine 12" Single-Voice-Coil 4-Ohm Loaded Subwoofer Enclosure Black SWT-12S4 - Best Buy
Amazon.com: Alpine ALP19-R-W12D4 Car Audio Type R Series Sub Dual 4 Ohm 1500W Peak 12" Subwoofer : Electronics
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Alpine Jeep Wrangler Single 12-Inch Alpine Halo R-Series Preloaded Subwoofer Enclosure with ProLink R2-SB12V (Universal; Some Adaptation May Be Required) - Free Shipping