JBL 102AM Stage Series 10" 4-ohm component subwoofer at Crutchfield
GT5-10 | 10 inch Subwoofer
Amazon.com: JBL Club WS1000 10" Shallow Mount subwoofer w/SSI (Selectable Smart Impedance) Switch from 2 to 4 ohm Bundled with Alphasonik Earbuds : Electronics