Atrend BBox Series Subwoofer Box for GM Vehicles (10" Dual Downfire, GM Crew Cab) in the Interior Car Accessories department at Lowes.com
Amazon.com: Atrend Bbox Dual Vented 12 Inch Subwoofer Enclosure - Pro Series Dual Vented SPL Car Subwoofer Boxes & Enclosures - Made in USA Subwoofer Box Improves Audio Quality, Sound & Bass -