Racer line, Tyr Sport, Inc. and Arena Powerskin line produce suits of this type. As with most technologically advanced fabric swimwear, kneeskin suits are only commonly used at highly competitive levels of the swimming sport and are known to sell for prices in excess of US$200. Jammer A jammer is a style of swimsuit worn by male swimmers, used mainly in competition to obtain speed advantages. They are generally made of nylon and lycra/spandex material, but may be made of polyester, and have a form fitting design to reduce water resistance. The materials usually dry fairly quickly. They provide moderate coverage from the mid-waist to the area above the knee, somewhat resembling cycling shorts or compression shorts worn by many athletes. They provide greater leg coverage than swim briefs and square leg suits, although they also have slightly more water resistance. Legskin A legskin is a type of competitive swimwear worn by male swimmers. Most legskins are made of technologically advanced lycra-based fabrics designed to hug the body tightly and provide increased speed and decreased drag resistance in the water. The legskin covers from the swimmer's mid-waist to his ankle and resembles leggings. One advantage of the legskin over other suit styles that cover the arms is flexibility, especially for strokes that require broad arm movement. Since 2009, legskins have been banned for competition swimming by FINA since they gave an unfair advantage to swimmers who wore them; the ban includes bodysuits. Racerback A racerback is a type of women's swimsuit design common today among competitive swimwear and incorporated into some types of women's clothing. The top-back of the swimsuit is not covered to provide flexibility and movement of the arms during swimming. Square cut The square cut or square leg style suit is a form-fitting male swimsuit used as a slightly less revealing style than swim briefs for water polo and diving, or for recreational wear. Like swim briefs, they are made of a nylon and spandex blend. They typically sit low on the waist and high on the thigh, but provide more coverage for the upper leg than briefs. The square-cut style was popular as a recreational swimsuit for men during the 1950s. Suits of this type are named for the coverage that they provide to the upper thighs due to a square seam opening for the leg. Square leg suits range in appearance from those similar to