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
Alpine Type R 12 Inch 2250 Watt Max 4 Ohm Round Car Audio Subwoofer | R-W12D4 - Walmart.com
Alpine SWR-1242D Type-R 12" subwoofer with dual 4-ohm voice coils at Crutchfield
LAB SlapBox™ 2.25 ft^3 Ported MDF Enclosure Box for Single Alpine 12" R-Series Subwoofer