Katie Couric sits in the stands of Arthur Ashe Stadium following the relentless on-court thwacks of the US Open tennis tournament. Curiously dangling from her ear is an American Express-branded blue lanyard. Hidden under her hair is an earpiece that’s letting her tune into ESPN’s live coverage of the match she’s watching.

Couric is just one of the handful of celebrities—and the thousands of fans—who have embraced American Express’s OneTune radios. Provided by Live Sports Radio and available only to American Express cardholders, the devices broadcast ESPN’s commentary to the US Open fans sitting in the stands, offering insight into the sport whose noise restrictions limit loudspeaker use during a match.

Though Instagram is filled with shots of the Open’s $23 signature Honey Deuce cocktail—made with vodka, lemonade, and raspberry liqueur—the somewhat dorky-looking headset has become the event’s most visible accessory.

The American Express radios are a hot commodity

The OneTune radios are a stalwart of American Express’s sponsorship of the Open. The company has partnered with the U.S. Tennis Association, which puts on the event, for 31 years. Of those years, AmEx has handed out radios for 24 of them.

“It is about keeping [fans] as close to the action as possible,” Suzuki says. “Whether they are sitting courtside at Ashe, or having their fifth glass of champagne out in the concessions, [they] stay close to that live commentary.”

Because they’re available only to American Express customers, the OneTune devices bring an air of exclusivity with them (cardholders can get one radio each day they attend the tournament). The radios are pre-tuned to a frequency that’s transmitted from the top of Arthur Ashe Stadium broadcasting ESPN’s coverage.

The branding also gets American Express some incidental celebrity coverage. Alongside Couric, actor Peter Sarsgaard wore the royal blue earpiece. Will Ferrell got some style coverage at this year’s Wimbledon for his newly gray hair (he was also sporting an American Express radio in his ear).

Last year, the radios facilitated a touching over-air moment. Tennis commentator Cliff Drysdale spotted actress Charlize Theron in the stands. She also happened to be wearing the OneTune. Drysdale expressed his praise for Theron, relating their South African heritage, before finally calling out to her: “Hey, Charlize. Hello! Oh boy, I had the guts finally to do that on air.” 

Theron gifted Drysdale with a wide smile and some air kisses.

With the celebrity moments and its visibility, Suzuki says the radio is a venue-appropriate add-on to the company’s already significant presence in Flushing. “It’s not obtuse—we don’t want to create things that feel out of place,” she says. “This is a very natural integration into its surroundings, [and] a natural integration for us with our brand as well.”

It’s not a necessity to enjoy the tennis matches, but the low-tech solution works on the grounds where cell service can be spotty and the Wi-Fi can be overloaded.

“Maybe you’re in between matches and you want to know what’s happening somewhere else,” Suzuki says. “You pull out your phone, and perhaps you’re able to pull up ESPN or not, but guess what? That radio is always going to be cranking.”