Support for belt of X axis so it is (nearly) parallel with the axis.
Suitable for Creality, Geeetech, Anet, Tevo, Tronxy, Alfawise, Raiscube, SainSmart, ... printers.
After printing, take off the belt stretcher (right side wheel). Leave belt on the carriage and slide in the printed parts one after another. Then put the wheel back on. It is easier then leaving the wheel on.