Summary This is a filament reel or spool holder for non-Dremel reels or spools. This holder holds the 1kg spools with an outside diameter of 200mm, width of 64mm and a hole diameter of 52mm (as supplied for instance by the 123-3D Housebrand) and "05kg core" core for holding the 0.5kg spools with an inside diameter of 50mm and a width of 40mm. It fits exactly inside the Dremel 3D20 printer. I fit this one on the right side of the printer so that I can both fit the standard Dremel filament or the other spool size (I used a mirror image of the filament guide for that: see amongst my other things). I do find that these reels are varying quite a lot in dimensions and that some touch the y-axis-stepper motor just a tad: I had to remove some flash from the reel to make them run smoothly. Fitting the holder requires opening the bottom cover and exchanging the two screws that are there with longer ones. Fitting the reel on the holder works best with the plate in the bottom position.