New y-idler with tightener, options to put belt guides with the bearing or not, it can be inserted with a clip, not need to take out all the threaded shaft. You need a 623 bearing, a M3 screw to fix the bearing, a M4 screw with hex head and a M4 nut. Parametric belt guide, stl adjusted for the y-idler (623) UPGRADE: stronger version, wharf option, stl ready to print. UPGRADE: more stronger, my hooks have been broken, so now they are more robust.