This is an subwoofer enclosure developed to use the Nomad PA1000-18 or Nomad PA1300-18 drivers. Some prototypes are being used with RockIjuí shows. 

And sounds flat and LOUD! 

Some technical advantages are:

 Have a pretty flat response, with a soft peak in 38Hz. It can down to 30Hz in a standalone application. Used coupled, they can go down below than 30Hz still with gain. Besides that, the External dimensions was projected to be more portable as possible, making its logistics cheaper.

About the design:

 The most common bass-reflex enclosures, uses a single vent port. This can difficult coupling the subwoofers to best, louder and lower response. Thinking about that, this enclosure was designed to offer the best coupling efficiency. The single vent port was divided into four triangles, located in the four corners. In a stand-alone application, this improves the sound distribution, both close to the ground, as close to the head. If used coupled, the point is: always the corners will meet. Besides that, the sound pressure level has a more cardioid distribution as possible.