The Bottom Line Vacumatics were more affordable models and did not carry the lifetime guarantee of the Top Line.
Bottom Line models were smaller and featured two cap bands. The clip screw and tassie jewels were always black (unlike Top Line models where they matched the pen).
Three sizes were produced:
Sizes may vary slightly, but these measurements are generally sufficient for identification.
Click the pen that corresponds with yours in size
From left: Junior, Slender Junior, Sub Junior.