The Moroso is 5".
Funny aside about the Moroso pully: I do my best to hide any aluminum and aftermarket mods in my engine compartment. I installed the aluminum pulley out of the package thinking it was buried to where no one would really see it. I went to a local cruise spot and literally the FIRST guy that walks up and looks at the engine points and says "Oh, it looks like you have an underdrive pulley!"
I went home, ripped off the pulley and immediately painted it black!