So I took apart the Hansgrohe Clubmaster in my master bathroom. It was easy to remove the white flow restrictor and now the Clubmaster rocks.

Inspired, I took the wrench to my Fantini rain head. Once I got it down I looked inside and there is a white plastic piece inside it as well. But this piece is a little more complicated: it has a moving cylinder within a cylinder. Also it is beneath a screwed in piece of metal-- there is a hexagonal opening, I'm guessing I need a special wrench to take it out?

I don't want to mess up the rain head. Anyone have any advice? I could post a photo later, I didn't think to take one when I took the head down.