Product review (3 stars): Same footprint as 4-inch models.
Nothing special, it does the job and seems to be as well made as anything else.  I was a little disappointed that it uses the same size louvers as the 4-inch models, so I could have just picked up a 4-inch at the big box and used an adapter.  I was hoping the 3-inch would have a smaller footprint.  Oh well, it works as well as any dryer to bathroom vent hood.  I had no problems with assembly or with the tin tube falling apart.