Polk Audio MM1242 SVC 12” Single Voice Coil Subwoofer with Ultra Marine Certification
Amazon.com: Cadence 8 Inch Car Subwoofer, High Performance 500 Watts Dual 2 Ohm 2 Inch Black Aluminium 4 Layer Voice Coil, Ultra Drive Series Car Audio Woofer UD8D2, Single : Electronics
Fingerhut - Polk Audio DB+ Series 1100-Watt Ultra-Marine Certified 12" Dual Voice Coil Subwoofer
Ultra Audio LV 8" 400 Watt Car Audio Subwoofer 800 Watts Max 4 Ohm USA Made | eBay
Adire Audio Kali 15" D4 - 3000w RMS XBL2 Subwoofer
Polk Audio MM842 DVC 8” Dual Voice Coil Subwoofer with Ultra Marine Certification
ASSAULT CLASS ULTRA 12 ACU12 – hammertechusa
Polk Audio MM1040 Ultra Marine Mobile Monitor Series 10" marine subwoofer at Crutchfield
Amazon.com: 2X SoundXtreme ST-712 12 Inch Sub 1600Watts Max Power for Pair Car Audio Shallow-Mount Ultra Slim Truck Competition 12" Subwoofer Single 4 Ohms Voice Coil : Electronics
Ultra Subs PRM-12 - Limited Run! | CarAudio.com - Car Audio Forum