Please excuse my ignorance
 

Tried searching this on my own but couldn't get any leads. Anyways, building 2 boxes to manufacturer specs for my two Hertz HX300 12's. Specs are metric and can't seem to figure out how to covert the port diameter or volume.
Can someone point me in the right direction?
Thanks!

Reflex Tube
Ø= AR 80V
L= 220 mm

Ø= AR 80V What is this supposed to be? Ø is the symbol for diameter, and if that is 80mm, then it is 3" diameter pipe but what is the V representing?

220mm = 8.66"

Huh. Only 1.25 ft^3? The 3" x 8.66" port tuned to 40hz sounds about right though.

1.25cuft sounds about the norm for a 'manufacturer suggested' box for a 12.

Personally, I would run it through a box design program and see what it really wants..

The Hertz manufacturers spec boxes are very well designed and you would be hard pressed to design a better box unless your prepared to make the box larger