Under Armour Inc is facing a proposed class-action lawsuit accusing it of misleading consumers about the purported performance-enhancing features of UA Rush, a mineral-infused fabric.

In 2019, Under Armour partnered with Celliant to create UA Rush, “designed to enhance performance, giving athletes that extra edge by recycling the body’s energy during moments of performance.”

The lawsuit said Under Armour’s claims that the Rush fabric works like “the fabric version of an infrared sauna” are not scientifically possible, according to Bloomberg. Infrared is unable to penetrate the skin and achieve the promised effects such as increased circulation, the lawsuit states.

Under Armour has not responded to the suit.

Photo courtesy Under Armour