JL Audio 10W1v2-4 W1v2 Series 10" 4-ohm subwoofer at Crutchfield
Amazon.com: Pyramid 12" 1200W Car Audio Subwoofer - 2 Way Neon Bandpass Speaker System w/ Blue Lights, DC 12V Input/4 Ohm/32Hz-1KHz Freq.Res w/ Plexi-Glass Front Window & Silver Polypropylene Cone - BNPS122 :
Denon Home Subwoofer - Subwoofer with HEOS® Built-in | Denon - US
Monitor Audio Silver W-12 Subwoofer in High Gloss Black Showroom Demo - AV Luxury Group
SUBWOOFERS
Canton Powered Subwoofer AS 5 Silver | eBay
Alpine Halo R2-Series Dual 10" Voice Coil 4-Ohm Loaded Subwoofer Enclosure Black R2-SB10V - Best Buy
INROOM SILVER SUB – Triad Speakers Online
Kicker Solo-Baric L7 04S12L7 12" subwoofer with dual 4-ohm voice coils at Crutchfield
Amazon.com: DS18 SLC12S Car Subwoofer Audio Speaker - 12" in. Paper Glass Fiber Cone, Black Steel Basket, Single Voice Coil 4 Ohm Impedance, 500W MAX Power and Foam Surround for Vehicle Stereo