For Jbl Boombox2 High-end 4 Inch 106mm Mid Bass Speaker Subwoofer 4ohm 40w Woofer Low Frequency Long Stroke 1pc - Speakers - AliExpress
JBL Stadium 102SSI Stadium Series 10" component subwoofer with switchable 2- or 4-ohm impedance at Crutchfield
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
JBL Studio 650P 10" 500W Subwoofer Wood JBLS650PWAM - Best Buy
JBL Stage 810 8" component subwoofer at Crutchfield
W12GTI II | 12 inch Differential Drive Design Subwoofer
JBL PRX915XLF Professional 15" 2000W Powered JBL-PRX915XLF-NA