For the last five years, Peter Beveridge has been innovating in the eye-black space. As founder of Eyeblack.com, he has sold eye black with logos on it to everyone from professional teams for use on the playing field to corporations handing them out as promotions.

Jacques Demarthon | Getty Images S Bethanie Mattek-Sands hits a return to Serbia's Jelena Jankovic during their Women's third round match in the French Open tennis championship at the Roland Garros stadium, on May 27, 2011, in Paris.

Looking to grow even more, having sold more than five million pairs of eye black last year, Beveridge has signed its first female spokesperson, Bethanie Mattek-Sands.

Mattek-Sands, currently ranked 31st in the world on the WTA Tour, has gotten plenty of attention for her use of eye black on the tennis court, not to mention her innovative outfits.

Mattek-Sands switched from sunglasses to eye black at the Australian Open earlier this year. After she tried Eyeblack.com's product, she says she could see better and also felt more intimidating.

Eyeblack.com now plans to use Mattek-Sands on retail packaging.

"Eye black is a perfect fit for tennis," Beveridge said. "It's mostly played outdoors and the ball is in the air, so this is a totally new market for us."

“Eye black has been a part of baseball and football for decades, so why not tennis now as well," Mattek said, in a statement. "I think as the players and our game evolve, just like the equipment has, EyeBlack.com can, too."

Eyeblack.com produces eye black in original, smear, clear and "warrior" and, on average, sells two pairs for $2.99. The product is made from latex-free medical-grade tape.

Beveridge says that a third of the company's business is through corporate giveaways, a third of the business is through sales at ballparks, in sporting goods retailers and at bookstores, and the final third is made up of its direct-to-consumer business on Eyeblack.com.

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