I don't understand the deal with the red focuser.

What's wrong with the focusers on these dobs; specifically what's wrong with the focuser on my new 8" dob?

I'm very happy with it, even though I don't know what some of the things sticking out of it are for, and I dare not touch them till I find out.

Seriously though, thanks to icemans description, I now know what that mystery screw on top of my focuser is for. I still won't touch it though.