JBL Club 1024 10" component subwoofer with switchable 2- or 4-ohm impedance at Crutchfield
Ported vs Sealed Subwoofer
BOSS Audio Systems P129DC Phantom Series 12 Inch Car Audio Subwoofer - 2600 Watts Max, Dual 4 Ohm Voice Coil, Sold Individually, For Truck Boxes and Enclosures, Hook Up To Amplifier - Walmart.com
Amazon.com: Sundown Audio SA-10 D2 Classic 10" Dual 2-Ohm 750W RMS SA Series Subwoofer : Electronics