Am i supposed to have an Alternator cooling duct?

So i'm assuming my alternator isn't original because i don't have the cooling duct under my hood that everyone seems to have on theirs, nor does the alternator have anywhere to hook the duct up to the backside. Is this OK? Do i have to have that? Do only some alternators require this duct?



I don't know which alternator i have it's just something i've noticed over time and finally got around to posting about it.