From their "FAQs & INFO Page"


Ventilation:

I have made a drastic improvement over other caging in the ventilation department. No more unsightly vent covers! No more need to leave stacks of cages apart because of the vent holes. No more need to leave cages away from the walls because of vents either. The venting occurs at the front of the cage. The door is mounted in such a way to allow a gap all the way around the door on the sides and at the bottom. This gap totals about 5 square inches! That is the same as a 5" x 1" hole for fresh air! This is about the same amount of ventilation you would have from two mid-sized unsightly vent covers. Great ventilation and no more vent covers that fall off and get dirty. Also improperly placing vent covers at the top of cages often creates a drafting or "chimney" effect allowing too much air to flow making it difficult to maintain consistent temperatures and humidity. Thought you might like to know!
I just got 2 of these last week, the 322Ds. I am completely happy with them. I will be buying more.