Compact 18" Portable Subwoofer System, 500 watt Crown® Class D Amplifier. DSP Featured Input Section with Selectable x-over. 18" VGC™ Vented Gap Cooled GC™ Woofer in a DuraFlex™-Covered, 18mm Plywood Enclosure, Steel Foam Backed Grille, Die-Cast Metal Handles and 35 mm Pole Mount Cup, Non-Skid Rubber Feet.