A heat-exchanging air-exchanger is typically an advantage only at temperature extremes; very hot and also running a 12v air conditioner. Or cold while also running the heat. That will allow one to still have air exchanged (what you typically do by having a window open) without "letting the bought air out" meaning the heated or cooled air. The air exchanger has a heat exchanger in it that will transfer some of the heated or cooled interior temp to the inbound cold or hot air as it's drawn in. That means less conditioned-air-temperature-loss (heated or cooled) and the heating and A/C systems don't have to work as hard compared to an open window air exchange, saving battery (for A/C) or fuel (for heat). If you are not running the heater or A/C at the time, then their isn't much of an advantage. Perhaps a small advantage, over a slightly-opened-window, is a bit more security and a bit less noise from outside.
That being said, something in me wants one. Ha. But not something needed.
It sits well in the "optional" category. Like the 12v A/C option, glad they offer it for those that use their campers in conditions where there is value in it.
