By directing the subwoofer diaphragm downward, the Pioneer 12 in. Downfiring Enclosure for the TS-SW3002S4 Subwoofer radiates bass with superior efficiency for richer, deeper low-frequency sound regardless of the enclosure’s installed position. The innovative, compact, space-saving enclosure design makes it easy for it to be installed freely in a variety of automobile trunk spaces or inside pickup truck cabins. The Pioneer TS-SW3002S4 12 in. shallow subwoofer itself is sold separately.