Wiper add-on necessary? See pic
 

So I went and got some cheapier Goodyear replacement wipers instead of going to the dealer. (The entire thing, not just the rubber blade.)

As I changed them I noticed that the OEM wiper on the driver side had this extra 'fin'.

Not sure what it's for and is it necessary?

If so, how do I transfer? I dont think it comes off (it looks like it's attached to the wiper).

Thats the wind deflector, its when your driving at high speeds in the rain it deflects the air hitting the windshield such that it maintains contact with the glass. You can try to see if it fits on your new Goodyear wipers. I think its held together with a few screws.

Thats to keep the wiper blade down on the window when ur going at higher speeds on the high way. and i changed my wiper blades to the rain x bracket less and did not need that part, but i am not sure if u need it for the good years.