The 1920 General Manufacturing Co. Snapfill #2 Lever Filler in black chased hard rubber is an unusual filling mechanism.
When you lift the lever from the barrel, a small hinged extension drops from the lever to the press bar. Pressing the lever then depresses the bar, filling the pen. When the press bar is fully depressed, the hinged extension then automatically snaps back into the lever and a “click” is heard as the lever lowers back into place into the barrel. Shown “open” in the photo. GF chased cap band; NP clip. General Manufacturing, in Sioux City, Iowa, also made the Houston Fountain Pen.