Big Red Senior from 1928–9 I own several Duofold Seniors.

The specific one shown in this post was made in 1928 or 1929[4].

Not content to rest on the laurels of its successful Duofold line, Parker began to research alternatives to the sac sometime in the mid-to-late 1920s.

Elaborating on an invention by a University of Wisconsin engineer, Parker came up with an all-new filler system and installed it on a new and visually-arresting line of pens that first went on sale in 1932.

The Ring Top would also appear on Parker's Vest Pocket models, for being attached to a watch fob.