Best Buy: Pioneer 12" Single-Voice-Coil 4-Ohm Component Subwoofer Black TS-W302R
Pioneer TS-W258D4 Champion Series 10" subwoofer with dual 4-ohm voice coils at Crutchfield
TS-A30S4 - 12" - 1400w Max Power, Single 4W Voice Coil, IMPP Cone - Subwoofer | Pioneer Electronics USA
Pioneer TS-1200M 12" - 1400 W Max Power, Single 4Ω Voice Coil, IMPP™ cone, Rubber Surround | Component Subwoofer - Walmart.com
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