Focal Sub 12 Performance Single Voice Coil 12 Inch 4 Ohm Car Subwoofer 300w RMSFocal SUB 12 SINGLE VOICE COIL SUBWOOFER SUBWOOFER LINE Designed and developed in France, the Sub 12 benefits from Focals sound savoir faire. With its 12 (30cm) polypropylene cone, this subwoofer provides an excellent bass boost for any on board audio system. It has a single voice coil architecture for simplicity and efficacy. A deep and powerful bass Effective as bass reflex or sealed box Sealed box from 15L Bass reflex box from 30L Robust design;