Hifonics ATLAS ATL12D2 Owner's Manual page 9

Subwoofer Dimensions
B
A
Due to the vented backplate, you must allow for an
additional 2" behind the subwoofer when designing
your speaker enclosure.
A - Cut Out Diameter
304mm / 11.97"
B - Mounting Depth
183.3mm / 7.22"
8