Alpine SWS-1242D 12" subwoofer with dual 4-ohm voice coils at Crutchfield
Alpine R-W12D4 12 inch 2250W Audio Subwoofer for sale online | eBay
Best Buy: Alpine X-Series 12" Dual-Voice-Coil 4-Ohm Subwoofer Black X-W12D4
Alpine SWE-1243 Type-E 12" Car Subwoofer
Amazon.com: American Sound Connection 312H Universal Large Car Trunk Triple 12" Sealed Subwoofer Rear Angle 3 Sub Box Stereo Enclosure and S-W12D2 Type S Series Sub Dual 2 Ohm 1200W Peak 12"
Amazon.com: Alpine SWA-12S4 BassLine Series 12" 4-ohm Subwoofer : Electronics
Amazon.com: Alpine S-W12D2 Car Audio Type S Dual 2 Ohm 1200 Watt 12" Subwoofers with Sub Install Kit Package : Electronics
Alpine R2-SB12V Single Type R2 12-in Subwoofer in Vented Enclosure - Creative Audio
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Alpine SWR-1221D 12" Dual 2-ohm Voice Coil Subwoofer at Crutchfield