Nippon brand new 12 single subwoofer tube box. with its 21 long tube and turbo vent underneath this is a big box that will help your woofers deliver big sound. and the 5/8 walls covered in charcoal-colored carpet mean this box will look great and be able to handle as much bass as you can throw at it. Woofer opening fits a 12 subwoofer approximately 1.37 cubic feet.