820-0010 stainless steel rods of 12 mm diameter have M6 male threads on the top and M6 tapped holes on the bottom. This allows to mount all accessories directly on the rod, or to fix the rod directly on movable bases, translators, or to connect the rods. The cross hole at the top of the rod is very convenient for rigid fastening.
The rod 820-0020-00 is especially designed for Precision Mirror Mount (eg. 840-0060) as well as for other mounts with mounting holes M4.
Rod 820-0020-20 has M4 male thread for the top and M6 thread hole at the bottom.