External rear spool holder tested on my x1 carbon, the project is composed of the main screw which must be screwed to the original seat of the original external spool holder using 2 3x15 screws, 2 threaded ring nuts which are screwed onto the screw itself to lock the spool in position so that it does not it slides off the screw by rolling, I tested it with 1 kg spools without problems and also with 250 gram spools without problems as you can see from the photos, don't tighten the 2 ring nuts too much otherwise the spool won't slide