14k Fine nib,
Parker 51 MKIV, Red barrel 1/10 12k Gold filled cap with grey jewel
Parker developed a sac in a tough plastic material, called Pli-Glass, that had a life expectancy of 30 years, but are now going on 60+. These sacs were also in a see through material which allowed one to see how much ink that was left in the pen. The sac was encapsuled inside a metal tube on which a metal pressure bar was mounted. To reveal this filling mechanism one had to unscrew the entire body cover from the section ring and back.