Got my grubbys on a west German PeliKan M150 fountain pen. But it was Busted the plastic Nut thing that draws the plunger/ ink into the pen was nonfunctional. Some CAD, Printer cleaning of crusty ink time later it works again. I Think this will fit many peliKan pens. The walls on this are <1mm so highly recommend (as i did) print in SLA VS FDM.