When the flappers were dancing in the 1920s, their male partners were likely to be wearing underwear in durable nainsook, a new woven cotton fabric that was just too, too "mod." Lots and lots of men and boys were still in union suits of various designs. Measurements of chest, waist and trunk (a circle measurement over the shoulder and under the crotch) were necessary to determine correct sizing.

The 1920s also saw the introduction of the first preshrunk fabrics in men’s underwear, as well as other new technologies. There was the self-insulating Duofold, Swiss American Knitting’s Navicloth and the no-button union suit from Hatchway. Unique advances appeared from Topkis Brothers, Allen A, and Vellastic. Carter’s boasted elegant cotton, wool and silk blends — and Robert Reis & Company announced their Jimsuits, Jimshirts and Jimpants.<<