square leg suit is a style that is more than a pair of swim trunks covering the body, used in general water sports swimwear, swimwear made of nylon and spandex. Popular casual swimwear in the 1950s. It is supplied to the upper part of the thigh and is named as a four-legged swimming trunk. It has only the difference in material with the boxer. Compared to other types of swimwear, the difference in fabric coverage is only a small difference in material, and there is also a "horse-type" swimming trunk with a length covering the entire thigh.

In 2002, Australia launched the 1970s fashion renaissance color flower and geometric retro pattern of swimming trunks, very popular with swimmers. In 2006, the styles of the four-legged swim trunks of the 1950s came back in the United States and Europe, and several fashion designer brands, including Versace and Dolce&Gabbana, introduced retro styles suitable for their catalogue, and Speedo in some South American countries ( Such as Brazil) to launch more mid-priced square swim trunks.