This part is a replacement of well known prusa i3 belt tensioner. One of image compare it. With this part you can adjust belt tension in front of printer on the fly. Suitable for threaded rods 10 mm in diameter. Distance between center of rods should be 20 mm. Stepper motor shaft is at height 29 mm. A very simple way to install and remove. You need only screwdriver. It is easy to adjust the position of the belt in a straight line. How to assemble. Consult with provided image. Insert part must slide slightly tight into main part to avoid backlash. Process printed parts surface with sandpaper if needed.