Just for anyone else in future wondering what a "Bat Brake" is, here is a nice little drawing of one:
<img src="http://www.smartgroups.com/vault/titchpics/bb.jpg">
If you use the Italian Hitch knot, combined with an appropriate krab for lifelining or assisted handlines, it can cause the rope to wear and twist, particularly if the rope is dirty. The "Bat Brake" is an alternative to the Italian Hitch knot and krab set-up and avoids all rope-to-rope contact. It looks very similar to a Belay plate, but is used entirely differently and the two should not be mixed up.