The JBL GT5-2402BR is two subwoofers built into an enclosure. This means that installation into a vehicle for this JBL speaker is much easier and requires fewer external parts such as another enclosure or specialized wiring. Each one of the subwoofers in this JBL GT5-2402BR speaker set is 12 inches in diameter and has a polypropylene cone woofer. The peak performance power of these speakers of 2200 watts for the set together, or 1100 for each one individually, which makes for very loud sound. As for the enclosure, it is designed specifically for this JBL speaker. It is wired for this car subwoofer set and has black carpeting on the exterior for appearance and durability. It is also ported, which helps to reduce heat overload and makes for a louder sound for a stunning musical experience. When this enclosure is installed in a vehicle, this JBL speaker set will provide solid, strong and clear bass.