Here's a "Before" picture of the back door and pull-down attic stairs.
Here's the "After" pic with the dryer vent installed.
(Notice the roof rafter? I left the attic light on)
Because it's one inch of sheet-rock, I used long deck screws and used PVC plates
on the top side, to act as 'nuts' to hold the vent from being shaken loose
by vibration from the blower.
The hole saw used, was 4.125", but the fit was too tight. I had to sand down the ID of the hole..
Amazon.com: MK Morse AV66 Hole Saw, 4-1/8-Inch Bi-Metal Boxed: Home Improvement
I used a dust mask! And went out on the deck to shake off.. Looked like a ghost..
Not real sure about the wisdom of using this directional vent.
It's nice that it will point the air flow in the right direction (downstairs),
but I fear it's going to generate a good bit of noise..