\rMost car subwoofer require a box, or an enclosure to work properly. The subwoofer box, or enclosure, provides the subwoofer with a fixed amount of air space to optimize performance. Virtually all of the car subwoofer we sell require an enclosure. Many marine\rsubwoofers are designed for free-air or infinite baffle applications and do not require an enclosure. You can purchase a loaded subwoofer enclosure to take the guess-work out of the box building process and ensure that you get a box that is perfectly designed and engineered for that specific subwoofer(s).\r