Team USA’s speed skating uniforms have sparked controversy over the unusual design choice of including a large grey circle highlighting the wearer’s crotch.

Under Armour, the sportswear company that designed the uniforms, insists that there is a scientific reason for the big grey crotch circles. The material covering the crotch and inner thigh of the athletes is reportedly called “Under Armour Glide,” and helps reduce friction and improve performance, the company says according to Yahoo Sports.

“We tested a multitude of friction guard materials to find the material that reduces friction the most,” the sportswear giant said in a statement. “Altering the color or using a material that comes in a different color would have rendered it considerably less effective.”

Under Armour claimed that the special material reduced friction by as much as 60 percent.

But many fans thought the grey highlights in an otherwise black uniform was a poor choice for Team USA.

Many took to Twitter to criticize the uniform design:

The Team USA speed skating uniforms have a grey patch down there… why?! That looks wrong. Discuss. #2018WinterOlympics pic.twitter.com/iwAH1QQD4T — Janelle (@janellemcleod_) February 20, 2018

Yo whoever designed the US speed skater uniforms is either a comedian, a pervert or both 🏾‍♂️ — richDollaz (@r33p04s) February 15, 2018

What’s up with the giant gray vagina circle on the #US women’s speed skater uniforms? Really unflattering design. #OlympicGames2018 — Lance Cranmer (@ChuckRamner) February 15, 2018

The uproar over the new “Under Armour Glide” patches is not the first time the company has come under fire for its uniform designs. During the 2014 Winter Olympics the company’s “Mach 39” uniforms were deemed so bad that skaters discarded them halfway through the games.

Follow Warner Todd Huston on Twitter @warnerthuston.