I don't remember it being between two towers, but it is a notable feature! On the way up, it is simplest to pass packs. The least timid climbs down a bit, to where the gap is just about 1.5 feet, then jumps or steps across the narrowest part. There is a broad horn on the "far" side of the gap, which one can use to set a belay, or anchor the rope/webbing for securing the packs.
On the way back, it is simpler to climb down on the left (mountain side) of the gap to ledges, then climb up the steep (but highly featured) wall.