Review (4/5): requires force to assemble.
The large guide is difficult to put onto the unit: it requires a lot of force, so much that it feels as though it will break. Once on, though, it adjusts easily by sliding. There are numbers which are supposed to allow the user to set it accurately, but they don't line up well: it's better to just put it on the shortest setting, then count clicks to get to the desired length.