Amazon.com: PIONEER TS-W3003D4 Champion Series PRO 12" 2,000-Watt Subwoofer : Electronics
Pioneer TS-W309D4 Champion Series 12" subwoofer with dual 4-ohm voice coils at Crutchfield
Amazon.com: Pioneer TS-A300D4 12 Inch 1500 Watts Max Power Dual 4-Ohm Voice Coil A Series Car Audio Stereo Subwoofer Loudspeakers / Free Alphasonik Earbuds : Electronics