Mitch Cahn was prepared for a slow summer.

But when Biden dropped his bid for reelection on July 21 and endorsed Vice President Kamala Harris, the game changed. And when Harris announced Minnesota governor Tim Walz as her running mate on August 6, the tide turned entirely. Within 24 hours, the Harris-Walz campaign sold about 25,000 of the $40 camouflage baseball caps manufactured by Cahn’s Newark, New Jersey-based business, Unionwear, the entrepreneur says.

Cahn’s company, which he founded in 1992 after purchasing the assets of a bankrupt baseball cap factory, has manufactured political merchandise since its inception. In its founding year, it made 150 caps for the Clinton-Gore ticket, but that line of business didn’t really take off until 2000, when Unionwear nabbed a significant order from the Gore-Lieberman campaign. “The internet made it possible for campaigns to actually sell merchandise,” Cahn says. 

In recent years, Cahn says that his company has received increased orders for senatorial and gubernatorial races. “Campaigns are raising much more money than they used to, and they have fewer places to spend it because there are a lot of bans on political advertising on social media,” he says. “So that money’s got to go somewhere. And I think that merch is one of the places the money ends up.”

Many political candidates, however, still see value in selling merch that’s both union-made and manufactured in the United States. Cahn says that Unionwear sees more sales from Democrats, but the company ultimately takes a bipartisan approach to business. “Unions traditionally voted Democrat so they have had to really play that up and make sure all of their merchandise was union-made,” he says. “Whereas Republicans did not specifically request union-made merchandise, although we are seeing that for the first time this year.”

Unionwear is not currently manufacturing any merch for the Trump-Vance campaign, though the company did make merch for the 2016 Trump campaign. Cahn estimates that “tens of thousands of vendors and embroidery shops” have manufactured former president Trump’s “Make America Great Again” hat since then. “The Trump campaign has allowed people to do whatever they want to get the logo and the color out there,” he says.

Unionwear doesn’t mix politics with business. “If we were a restaurant, no one would ask me if we allowed both Democrats and Republicans to eat here,” Cahn says. “We can’t discriminate against anyone who wants to buy merchandise.”

And this time around, supporters of the Harris-Walz ticket really want to buy merch.

After the June 27 debate between Biden and Trump, Cahn had an inkling that the former would eventually step down from the Democratic ticket. “That’s when we started to prepare for a potential surge in orders,” he says. The company shifted some of its production deadlines from September to October to free up capacity and made thousands of baseball caps that were ready to be embroidered; if necessary, the company could outsource that part of production to other embroidery shops to accommodate a surge.

For a typical presidential campaign year, Unionwear anticipates selling 2,000 hats a day–a rate that Cahn says Harris has surpassed. Sales of Harris-Walz merchandise have outpaced projections, he adds, but the real viral hit is the campaign’s camouflage hat, with the running mates’ names inscribed in orange.

“We were not anticipating a camouflage hat,” Cahn says. “I don’t know if they were either.” The design isn’t unfamiliar to Unionwear–the company has manufactured similar hats for hunting organizations and labor unions–but it captures a diverse demographic. The design is a play on traditional hunting gear, but for those in the know, it’s also a reference to a similar hat currently sold by the 26-year-old Missouri native popstar Chappell Roan, who has skyrocketed in popularity in recent months and, this weekend, drew the largest crowd in Lollapalooza history, a spokesperson for the music festival told CNN.

After seeing Walz in a camouflage hat on Tuesday–in the video Harris posted of the governor accepting his position as her running mate–the Harris-Walz campaign design team conceptualized the camo hat by around noon that day and developed prototypes by 1:30 p.m., Fast Company reported.

Cahn says that Unionwear messengered a camouflage Harris-Walz hat to Philadelphia–ostensibly the one that Walz himself was photographed wearing Tuesday evening–and the company prepared samples to be shot for the campaign’s website. Since Tuesday, several others, including Walz’s daughter Hope, and members of the band Bon Iver, which performed at the Harris-Walz Wisconsin rally Wednesday, have sported the design.

The hat’s original run of 3,000 hats sold out in 30 minutes, according to the campaign, and now the product is currently on preorder, with an expected ship date of October 14. In spite of the wait time, customers are still placing orders.