Amazon.com: Alpine R-W10D4, R Series Dual 4 Ohm Voice Coil 2250 Watts Subwoofer, 10" : Electronics
2 10 inch alpine type r's super BASS - YouTube
Alpine SWR-1042D Type-R 10" subwoofer with dual 4-ohm voice coils at Crutchfield
Alpine SWR-1042D Type-R 10" subwoofer with dual 4-ohm voice coils at Crutchfield
Amazon.com: Alpine ALP19-R-W12D2x2wKit Car Audio Type R Dual 2 Ohm 1500 Watt 12" Subwoofers with Sub Install Kit and HA-SWKD Dual Sub Box Install Kit - 16 Screws and Speaker Wire with