Alpine SWR-1042D Type-R 10" subwoofer with dual 4-ohm voice coils at Crutchfield
Alpine R2-SB10V Single Type R2 10-in Subwoofer in Vented Enclosure - Creative Audio
Universal Car Stereo Slotted S Port Single 10" Alpine Bundle Type R R-W10D4 Sub Box Enclosure with Harmony HA-A800.1 Amplifier & 4GA Amp Kit - Walmart.com