Please, use adequate ventilation (with a heat exchanger if you need to keep A/C in the room) if you're going to be resin printing inside. I don't want to see all of you guys get cancer from this hobby.
It's essentially a heat/cooling recovery unit so you're not simply pumping your A/C out into the world and wasting energy. It allows you to swap the air in a room out, without losing its cool/heat by simply pumping in outside air. The video explains what he used.