The GC3 grips showed up today, overseas here where I am right now. They look like they just slip onto the bars.

Because they are supposed to be oriented at an "appropriate angle" to provide support for the hand, I wonder how the angle is "fixed". The allen screw at the end seems to only adjust the bar. How do you keep the grip (and thus the bar-end) from moving "forward or backward" on the handlebar?

TIA