Product review (4 stars): High Capacity Roof Jack
This roof jack is high capacity suitable for high airflow kitchen hoods.  I installed it for a Vent-A-Hood dual blower kitchen hood, and it is large enough to handle the 600 CFM airflow.

The quality is good, sheet metal with baked enamel finish.  As opposed to plastic roof jacks, roofing cement can be used in direct contact with this product.  The installation instructions are adequate.  This was my first experience with roof shingled openings, and installation was relative intuitive.

The birdscreen is removable for access to the backdraft damper, which is also removable for replacing the gaskets.

I gave it 4 stars instead of 5 because it lacks an adapter for the inlet ductwork.  The inlet on the underside is simply a large opening of size approximately 10.5" x 11".  I added a flat sheet metal adapter with an 8" diameter hole, which I fastened to the underside of the roof cap with sheet metal screws at the four corners of the opening (inside of its weather cap).  I crimped and inserted the 8" dia duct from the hood into this adapter from the underside of the roof.