Amazon.com: 6.5 Inch Car Woofer Speaker - 300 Watt High Powered White Injected Polypropylene Cone Car Audio Sound Component Speaker System w/ High-Temperature Kapton Voice Coil, 4 Ohm, 40oz Magnet - Pyramid
Amazon.com: BOSS Audio Systems CXX8 8 Inch Car Subwoofer - 600 Watts Maximum Power, Single 4 Ohm Voice Coil, Easy Mounting, Sold Individually : Electronics
Amazon.com: Pair of E-12 V.3 D4 - Sundown Audio 12" 500W RMS Dual 4-Ohm EV.3 Series Subwoofers : Electronics
Amazon.com: GRS 3FR-4 Full Range 3" Speaker Driver 4 Ohm : Electronics
CocinaCo 40mm 4Ohm 5W Full Range Audio Speaker Bass Loudspeaker: Amazon.com: Tools & Home Improvement
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Amazon.com: Fielect 2Pcs DIY Magnetic Speaker 3W 4 Ohm Full Range Audio Speaker Stereo Woofer Loudspeaker Replacement for Arduino, 52mm Diameter : Electronics
Amazon.com: Pyle 6.5 Inch Mid Bass Woofer Sound Speaker System - Pro Loud Range Audio 300 Watt Peak Power w/ 4 Ohm Impedance and 60-20KHz Frequency Response for Car Component Stereo PLG64 : Electronics
Amazon.com: Skar Audio EVL-15 D4 15" 2500 Watt Max Power Dual 4 Ohm Car Subwoofer : Electronics