TRU SPEC Prefab Quad 6.5" Sub Up Port Back Subwoofer Enclosure
Every Tru Spec enclosure is computer designed, CNC cut, and assembled inhouse at GPcarAudio. 
Tru Spec Prefabricated enclosures are simple, straight to the point, true to spec sub enclosures with proper airspace and non restrictive port area that allows you to have custom box performance at a reasonable price. 
TRU SPEC PREFAB 4x 6.5" Sub up port back with double flush baffle
Material: 0.75" MDF
Total woofer displacements factored in: 0.24  cuft ) *What does this mean? You will have 2.5 cubic feet of internal volume AFTER your sub displacements.  (Many 6" are around 0.06 cuft each)
Total Airspace per subwoofer: 0.625 cuft
 
Box External Dimensions
Width × Height × Depth
30.00" × 16.50" × 15.88"
Material Thickness
0.75"
Net Internal Volume
2.50 ft3
Tuning Frequency
35 Hz
Port Area
37.13 inch2
 
 
 
Cutout Diameter: 5.95"
Flush Trim Diameter: 7.5"