Focal Sub 10 Performance Single Voice Coil 10 Inch 4 Ohm Car Subwoofer 250w RMSFocal SUB 10 SINGLE VOICE COIL SUBWOOFER SUBWOOFER LINE Designed and developed in France, the Sub 10 benefits from Focals sound savoir faire. With its 10 (25 cm) 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 10L Bass reflex box from 25L Robust design;