JBL Grand Touring Series GTO1004D 10" subwoofer with dual 4-ohm voice coils at Crutchfield
Amazon.com: JBL Club WS1000 - 10” shallow mount subwoofer w/SSI™ (Selectable Smart Impedance) switch from 2 to 4 ohm, Black : Electronics
JBL S2-1024SS Series II 10 Inch Subwoofer with SSi Selectable Impedance - 2 or 4 Ohm - Creative Audio
JBL 10MG1200 10" Professional Mid-Bass Speaker 1200 Watts
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