Thanks for everyone's input on OAKs. I have decided to use fresh air intake on my Ecoteck, Monica stove. The intake is metric and smaller (OD is 35 mm) than the intake on US stoves. I don't want to use an adapter and increase the size to 2" in order to use stock hose. I prefer a cleaner look and may go with thin wall SS pipe in metric size. It would be nice to find a flex hose with the correct ID. That way I could adapt a hole in my existing wall thimble. If I go straight out the back of the stove, I will need another hole in the wall. Is there an appliance adapter that goes from 80 mm to 3" and has a built in fresh air intake of 35mm?