This is an axle for the idler bearing for the Greg's Wade's hinged accessible extruder. This way you don't need to cut a tiny section of 8mm smooth rod. Note: I used slic3r for this part, which sometimes has problems with accurate dimensions. It might be too small if you use some other slicer (ie Skeinforge?) that is known to be a bit more accurate. Okay, so this must look silly since you could make this on your own with one line from OpenSCAD in just as much time as it took to download the stl for this Thing. SO WHY ARE YOU READING THIS??? GO AND MAKE ONE!! :-D1: Print and insert into the inner race of the 608 bearing. 2: Press into the Guidler.