i personally love the sabra mounts. really flexible system.
the hex bar does indeed come in 1 meter lengths from posthorn, as mentiond above. If you are in a pinch, or need a longer bar, most hardware stores carry round alluminum rod of the same diameter. It will usually be much cheaper than the expensive hex bar. The hex bar is more stable as it wont spin in the mount, but it is also limited in its ability to rotate. The round bar allows you to rotate the mounts and is suprisingly stable.... The hardward store rod can be turned black with a little spray paint or a paint marker for really small rods...