20s vintage ladies wool knit swim suit with a art deco style label at the front, a Jantzen 'swimming suit' marked for the The Collage Shop in Madison Wisconsin.
This isn't in perfect condition (there's some moth holes and a few spots) but it's a good early piece with dated label from the 1920s (see close up of the Jantzen label).
It's 'flapper' sized for a slim collage girl, 28" at the bust, 28" at the hip. Torso length is also 28".