BOSS Audio Systems BE8D Elite Series 8 Inch Car Audio Subwoofer - 600 Watts Max, Dual 4 Ohm Voice Coil, For Truck Boxes and Enclosures, Hook Up To Amplifier
What is the difference between a single coil and a double coil in speakers? - Quora
6.5" NITRO SERIES SUBWOOFER 400 WMAX/200 WRMS DUAL COIL 4 OHM VOICE CO – GENIUS AUDIO USA
Focal Sub 10 Dual 10" Subwoofer, Dual 4-ohm Voice Coil, 250w Rms - 500 W Max : Target