Don't know why MassDrop keeps saying this cap is not meant to be posted. It does post, and feels fine when posted. The cap just needs to be firmly pushed onto the barrel until you hear a click, and then the cap is firmly posted. Posters, do not be discouraged! This is a #6 nib by the way.
yorgasorSomeone on MD had to tell me this a month ago. It is a very deep poster, and goes from rattly and loose to solidly fixed with a little bit of effort and an audible "click". Its a strange design, but works well once you know the "trick".
yorgasorMr. Pen should probably include that in the instructions for this pen, as none of the other pens I have from the Italix brand work that way. The rest all just post normally by a sort of simple push to hold with no magical click needed.