Welcome to the forums! I'll move you to HVAC for a better response....
Most hood fans are 7"dia. or 3x10", insulated/vapor barrier where they go through unconditioned spaces (anything to help keep the grease from sticking/moisture condensing).
If any ads are present below my answer or words underlined/colored, I do not condone/support/use the product or services listed/linked to, they are there without my consent.
WELCOME to the forums, if I forgot to say it!