Alpine SWR-1522D Type-R 15" subwoofer with dual 2-ohm voice coils at Crutchfield
ALPINE TYPE-R 12 Inch 30cm DVC Subwoofer BOX Set | Sub Woofer with BOX | Croooober
Ported (Recessed) Sub Box Enclosure for 1 15" Alpine Type-R SWR Subwoofer -32 hz | eBay
Memphis PRXA600.1 Power Reference Series Mono Subwoofer Amplifier and a Alpine S-SB12V Pre-Loaded S-Series 12-inch Subwoofer Enclosure - Creative Audio
Alpine SWR-1521D 15" subwoofer with dual 2-ohm voice coils at Crutchfield