I'm installing an over the stove microwave during my kitchen remodel and want to vent it to the outside to better remove cooking odors and smoke. I have not chosen one yet as I haven't had the time to research them yet, but I need to do the rough in so I'm ready to go when I do decide on one. Does anybody know if the rough in is standard for the vent between all manufacturers, or are they different? If it is standard, what are the dimensions, and what size duct connects to them?