The history of contraception for men is riddled with setbacks: Promising studies have failed, or been shuttered over safety concerns. Funding has dried up after years of fruitless attempts. Biology has proved surprisingly stubborn.

But for Michael Sworen, a restaurant worker from Seattle, Washington, the biggest obstacle to obtaining a male contraceptive was the office where he had to get it.

“I had to walk down this long, dark hallway that’s got lights flickering and it's all gray cement,” Sworen told The Daily Beast. “They let me into their office and you see computers from the 1990s that shouldn’t be running anymore, and they have a couple experiments sitting in water.”

“I’m like, ‘What have I gotten myself into here?’”

Sworen is one of more than 400 expected participants in the phase II trial of the first male contraceptive gel. The office he entered in Seattle that day is one of nine sites across the world helping to test the product, which experts say is the most promising male hormonal contraceptive now being tested. Couples everywhere from Scotland to Kenya have volunteered to use the testosterone-blocking gel daily for more than two years, in hopes of solving the male birth control conundrum.

"This is the first time that we will actually have men—similar to the female pill or some patches that women use—administer the contraceptive themselves,” said Dr. Stephanie Page, who is heading up the trials at the University of Washington School of Medicine. “Seeing the launch of a trial across multiple continents and centers is really exciting.”

The product Sworen is testing, called NES/T, is a progestin compound combined with supplemental levels of testosterone. The compound, also known as Nestorone, is the same one found in some female birth control rings. Applied on the back and shoulders and absorbed through the skin, it blocks testosterone production in men, temporarily reducing the amount of sperm until the user is, effectively, shooting blanks.

The gel, developed by the Population Council and National Institutes of Health, is specifically formulated to avoid the pitfalls of other, failed male contraceptives: The testosterone was added to make up for the reduced hormone levels in the testes, and to prevent such side-effects as low sex drive and mood swings. The product is applied topically for a more controlled release, and because neither progestin nor testosterone remain in the body long enough when taken orally.

The initial results are promising. In a six-month study of nearly 100 participants, the product successfully lowered sperm counts to infertility levels in nearly 90 percent of men, with few side-effects—though none of the participants actually used it as their sole contraceptive.

The demand for such a product is massive. A study of nearly 2,000 men in Edinburgh, Cape Town, Shanghai and Hong Kong—and another of more than 9,000 in nine different countries—found the majority of men are open to using a hormonal contraceptive. Researchers in the 1990s once estimated that a new male contraceptive could commandeer as much as half of the $10 billion female contraceptive market.

But progress has so far been slow. Biologically, male birth control is harder to develop because men simply have more sperm than women have eggs. It’s also difficult to secure funding for male contraceptive research, given the higher standards and lower tolerance for side-effects than when female pills were developed in the 1950s.

There have also been some scary setbacks. Trials for one promising sperm-suppressant injection were shut down in 2016, after a number of participants developed acne, mood swings, and severe depression. At least one participant attempted suicide.

The Daily Beast spoke to two of the men in the Seattle contraceptive gel trail, who were the first to speak publicly about their experience. Both were in their thirties, married with at least one child, and both worked jobs flexible enough to accommodate monthly visits to the test site.

Sworen, 30, said he found out about the study through an ad on Reddit, while Nathan Yoder—a 32-year-old bank teller and substitute teacher—heard about it on the local news.

“It kind of sounded like the future, in a way,” Yoder said. “I keep telling my wife, ‘In 20 years it will be just over-the-counter type medicine.’ It will be cool to say, ‘Oh, we were the test subjects; we were the guinea pigs for this.’”

The test subjects—of whom there are currently about 20—signed on for nearly two years of testing. The men must apply the gel daily for up to 16 weeks, or until their sperm count is down, and then use the gel as their only means of contraception for 52 weeks. After discontinuing use, they will remain in the study for up to 24 weeks for observation (and to make sure their sperm count returns to normal.)

Both Sworen and Yoder have been in the study for about two months. Though neither have reached a low enough sperm count to be considered infertile, both seem pretty excited about the whole process.

"You just add a little extra thing in your morning routine,” Yoder said. “I put on my deodorant and I put the gel on and then I get dressed, so it’s really no hassle or inconvenience.”

Sworen, meanwhile, applies the gel at night—after putting the baby down, but before getting in bed. Users are supposed to avoid skin-to-skin contact for at least four hours after application, so both men said they’re vigilant about putting on a shirt before hugging their wives or holding their children.

Both men said they enrolled in the study in order to take some pressure off their wives. Women account for three-quarters of all contraceptive use worldwide, and Yoder and Sworen’s wives are no exception. Both women have been on various forms of birth control for years, and neither has particularly enjoyed it.

“She's just been gone through this whole gauntlet of different birth controls—shots, IUDs, pills,” Sworen said of his wife. “Some of them make her crazy, some of them kill her sex drive. And it’s nice to just be able to take some of that burden off of her and onto myself for once.”

Despite watching their wives go through birth-control hell—and despite reports that several of the first trial participants experienced acne, mood swings, headaches or insomnia—both men seemed relatively unconcerned about the side-effects of a hormonal contraceptive.

“I have a little bit more acne on my shoulders from the gel, but I feel like it’s a small price to pay for something that could be quite convenient for people,” Yoder said.

Sworen joked that he was keeping an eye out for “man-boobs,” but that so far, any side-effects had been largely positive. “I feel like I’ve gained a little bit of muscle mass over the last couple of months,” he said. “Not complaining there.”

The men’s attitude may seem odd, but it’s surprisingly consistent with past studies: In the injection trial where one man attempted suicide, 75 percent of the participants said they wanted to continue using the product after the trial was shut down.

Megan Kavanaugh, a contraceptives researcher at the Guttmacher Institute, found the men’s perspective refreshing.

“There’s always been this narrative in the field that male contraceptive methods won't work because men wouldn't accept a high level of side-effects,” she said. “Maybe things are shifting and changing. Maybe it’s reflective of the broader societal move toward more gender equality.”

Both Yoder and Sworen said that, despite some gentle ribbing from their friends about going sterile, they felt the product would be an instant hit with other men. They argued that men are eager to take pregnancy prevention into their own hands, but feel trapped by the current, limited options.

“I always wished there were more options for guys as far as contraceptives go,” Sworen said. “Because nobody likes using condoms, and other than that you really have to rely on the girl— that she’s taking it every day and that she is really doing what she says she’s doing.”

The product isn’t about to hit shelves anytime soon. The current trial will take about three years, and a larger Phase III test will take longer still. Then it’s on to FDA approval, which could take anywhere from six months to two years. The researchers estimate they’re about 10 years away from having the drug on the market.

But if the product does prove successful, and makes it to supermarket shelves, would Sworen and Yoder be interested in using it?

Again, both men’s answers were surprisingly simple.

“It depends on the price point,” Sworen said. “If it’s comparable to what we’re already paying for a pill, then absolutely.”