Alpine R-W10D4 Type R 10" Dual 4 OHM Subwoofer with GTR-601 Mono Subwoofer Amplifier 600 watts RMS x 1 at 2 ohms - Creative Audio
Alpine S-Series 12" Dual-Voice-Coil 4-ohm Subwoofer Black S-W12D4 - Best Buy
Alpine SWE-815 SUBWOOFER ATTIVO DA 20 CM DA 300 WATT – Audioevolutionhifi
Alpine Jeep Wrangler Single 12-Inch Alpine Halo R-Series Preloaded Subwoofer Enclosure with ProLink R2-SB12V (Universal; Some Adaptation May Be Required) - Free Shipping