Amazon.com: Facmogu 2PCS 6.5in Full Range Speakers, RMS 30W MAX 50W, 4 Ohm HiFi Full Range Car Audio Speaker Drivers, Wideband Stereo Audio Loudspeaker Replacements - Red : Electronics
How to stop worrying about speaker impedance - CNET
What Is An 8 Ohm, 4 Ohm, 2 Ohm Or Other Impedance Speaker?