I recently inspected a home and I was not able to identify what this device is.
The silver hose/duct runs into the master bedroom closet ceiling. The vent inside the closet looks like a normal AC ceiling vent.
I have contacted my HVAC friends and a HVAC supplier, no one has been able to positively ID this.
Thank you for your assistance!
*This was as close as I could get to the device due to the owner having the attic full of their personal items.