This is a Wahl Zigzag Design 12 karat yellow gold filled small size model 437A clip fountain pen c. 1921-1924. The Zigzag Design is a repeating pattern of wavy lines in a zigzag around the cap and barrel. This 4 5/16 inch long pen is the small size slender model that normally comes with a with a 14 karat gold Number 3 size nib. This nib is possibly a replacement Number 2 size, that would fit the ringtop. Two Ringtop size pens and 3 clip pen sizes were made with this design. The barrel has a rectangular blank for engraving. This model sold for $7.00.