Pioneer 12 Inch Subwoofers TS-A301D4 / TS-A301S4 System Overview - YouTube
Amazon.com: Pioneer TSW312D4 Champion Series 12" 1500 Watt Dual 4 Ohm Voice Coil DVC Car Subwoofer : Electronics
Amazon.com: Pioneer TS-M800PRO 8-Inch PRO Series High Efficiency Mid-Bass Car Speaker Drivers - Pair (Discontinued by Manufacturer), Black : Electronics
Pioneer TS-Z10LS4 Z Series shallow-mount 10" 4-ohm subwoofer at Crutchfield
Amazon.com: PIONEER 12" Single VC 1400W : Automotive