This pen is difficult to categorize. I have not had the opportunity to handle one, let alone take one apart and investigate the filling system. It sounds like the cam-style barrel end mechanisms (Turnstile and Matador), but with a joint in the middle. The Clickit article from 2008 (below, courtesy of Pete Sacopulos) states that twisting the barrel joint activates a “tweezer-like” mechanism, which seems to say it is not a standard pressure bar like the cam style systems.
Click-It-Fountain-Pen-Article