That kit uses a half-length (approx.) "Cross"-type refill, I believe. . The click mechanism is at the top end, and there is an extension rod going between the click mech. and the top of the short refill.
I don't like "Cross"-style refills and so I am not much interested in it. . I have not tried it but I am going to watch this thread to see what develops because the concept, in general, is of interest.