99-2006 Chevy Extended Cab 2-12'' Ported Poly subwoofer boxFits 99 2006 Chevy Extended Cab The hardest hit sub box for the Chevy Extended Cab Armor Coated With High Pressure Polyurethane Bed Liner Material Increases The Base up to 4 times , stiffens the wood and no air leaks. 2 12'' Speakers Front Firing System Ported Sub Box Fits Under The Rear Seat Air Volume 1. 83 Cubic Feet total no divider (mono) Mounting Depth 9'' with the Magnet diameter less than 6'' Material 5 8'' M. D. F Dimensions: 56" x 18" x 14"