string rod (?) right after the locking nut question

[Smegolas]

whats the rod after the locking nut that the strings go underneath before they go to the tuners called? what is its purpose? how high should it be set - anyone have some pics of the correct height?

i got my rgt back from the shop and am suddenly having a hell of a time tuning it, am wondering if its set too low?

[LonePhantom]

String retainer - you want to screw it down far enough that the strings are making proper contact on the back of the nut, but not too much that they get caught up between the retainer and the headstock.