One side is in and one side it out. Careful, that hood uses 6 inch pipes. I don't know which ones use 4 inch pipes so either way be sure to buy matching equipment.

I'm not sure what you mean by "how does that hood work". The fan does the work and the pipes move the air. All it does is keep the bulb head in the vent system and not in your room/tent. it does the reflecting like your regular hood. I'm not sure how you'd hook up a filter with a hood with only one vent flange so again put your system together with a good plan and research.

Doc Oc