Alpine SWR-1221D 12" Dual 2-ohm Voice Coil Subwoofer at Crutchfield
Amazon.com: Alpine R-W12D4 Car Audio Type R Series Sub Dual 4 Ohm 2250W Peak 12" Subwoofer and HA-SWKD Dual Subwoofer Sub Box Install Kit : Electronics
Amazon.com: Alpine ALP19-R-W12D4 Car Audio Type R Series Sub Dual 4 Ohm 1500W Peak 12" Subwoofer : Electronics
Insane Bass From Two 12" Alpine Type R (SWR12D4) Subwoofers!! - YouTube
Alpine 12 Inch Type-S Subwoofer (SWS-12D2/D4) | SK Customs Car Audio & Home Theater | Atlanta | Norcross | Duluth | John's Creek