It was what Bassbox Pro program suggested when I choose the option for it to do that so don’t put much faith in it. I’m going to guess Sundown can’t fit a vent in a box any smaller. For reference my JL Audio microsub with the 8W3v3 subwoofer was installed in a box just .35 cu ft tuned to 35 Hz by JL Audio. It’s only an 8” subwoofer after all. I normally put a 10” in a ported box around 1 cu ft such as the Alpine and Sundown SD3 10 I own.Seriously?! .244 ?! That's like a third of my current box and seems very very small. Sundown themselves recommend .5-.75? Why so small?