ok, in the brake fluid resevior (sp?) there is a piece attached to the cap that i believe pushes the air out of it when u put the cap on it, but my clutch fluid resevior doesnt have that, instead it just has a piece of plastic floating in it, its a round disc with a raised notch/line in the center on both sides, what is that thing? and what is it used for?

 

I believe that just catches debris that may fall into it.

 

hmm, its not big enough to do that