STLF-1804-4 | 18" 450W Raw Woofer Replacement Speaker, 4" Voice Coil, 4-Ohm – Sound Town
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Dayton Audio DCS255-4 10" Classic Subwoofer 4 Ohm
Amazon.com: Pyle Car Subwoofer Audio Speaker - 8in Non-Pressed Paper Cone, Black Plastic Basket, Dual Voice Coil 4 Ohm Impedance, 800 Watt Power and Foam Surround for Vehicle Stereo Sound System -
Pyle Single Voice Coil Car Subwoofer - 8 Inches, 200 Watts at 4-Ohm Car Audio Powered Subwoofer - Walmart.com
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Rockville W12K6D4 V2 12" 2400w Car Audio Subwoofer Dual 4-Ohm Sub CEA Compliant
Amazon.com: Pyle 8 Inch 1600 Watt DVC 4 Ohm Car Audio Subwoofer Speaker Set with 40 Oz Magnet and 1.5 Inch 4 Layer Voice Coil, Black (2 Pack) : Electronics