Front loaded subwoofer enclosure using a high efficiency 4" voice coil 18" low frequency driver. Constructed from 3/4" (18mm) birch plywood, finished in black textured paint (optional TurboBlue, white, or raw birch plywood). The cabinet is fitted with M10 internal steel rigging points for permanent installations using standard eyebolts. Speakon NL4MP and terminal strip connectors.