Holds the bar / rod. Typically you need two of them left and right to the bar. I lost one when I moved the last time. So this is my very first project from bottom up after printing some of the designs I found here. It was made with OpenScad, then exported to STL and converted with Cura to Gcode. V2 has an additional support (reinforcement) and is better parameterized in the .scad for easier editing.Just edit the variables in OpenScad and fiddle with the values to adjust it to your needs.