TRU SPEC Prefab Dual 6.5" Subwoofer Enclosure Sundown SA / DC M3
 
 Tru Spec Prefabricated enclosures are simple, straight to the point, subwoofer specific enclosures dialed in precisely to manufacturer's specifications after displacements. These subwoofer specific enclosures will be versatile to many other subwoofers as well, so you do not have to use the noted driver on the enclosure, just be sure and double check your cutout.
TRU SPEC PREFAB Dual 6.5: Sundown SA-6.5"/ DC M3 6.5" with double flush baffle
Material: 0.75" MDF
 
Box External Dimensions
Width × Height × Depth
20.00" × 9.00" × 11.66"
Material Thickness
0.75"
Net Internal Volume
0.60 ft3
Tuning Frequency
40 Hz
Port Area
8.00 inch2
Cutout Diameter: 5.95"
Flush Trim Diameter: 7.50" 
Also fits the following 6.5" Subwoofers and are close to recommended specifications:
DC Audio M3 6.5" Subwoofer (this enclosure is spot on to DC's suggested specs after displacements.)
CT Sounds Meso 6.5" subwoofer 
CT SOunds Tropo 6.5" subwoofer 
Massive Hippo XL 6.5" Subwoofer 
DS-18 Elite Z 6.5" Subwoofer 
Rockville W6k9 6.5" Subwoofer 
Skar EVL 6.5" Subwoofer 
Audiopipe TXX BDC4 6.5" Subwoofer 
Ampere Audio AA 6.5" RVE