The menstrual disc startup acquired another startup, Keela, a Kickstarter-backed company that makes a reusable menstrual cup designed for easier removal. Flex also announced it’s raised $3.6 million this year from BOW Capital, Quest Venture Partners, Halogen Ventures, and its former accelerator Y Combinator, bringing its total funding to $7.9 million.

“Startups typically don’t acquire other startups. It’s pretty rare,” Flex CEO Lauren Schulte said. “But it made a lot of sense for us to work together instead of to compete with one another.”

Flex, which offers a disposable menstrual disc that’s an alternative to tampons, pads, and other period products, had been trying to develop its own menstrual cup. A reusable product, the cup appeals to customers who want an environmentally friendly period product. The disc, by contrast, is a disposable product that sits near the cervix as a diaphragm would. Flex is part of a wave startups—including Lola, an organic tampon company, and Thinx, which makes period-proof underwear—trying to create innovative products that allow women to approach their periods in new ways.

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“People don’t understand the difference between a cup and a disc,” Schulte said. “We had been working on a cup of our own because we fundamentally believe there’s no one period product out there for everyone.”

Rather than continue to pursue a cup product of its own, the two-year-old company reached out to Keela, which was just moving out of its Kickstarter phase. Conversations between the two like-minded startups eventually turned toward acquisition talks. Keela co-founders Jane Hartman Adamé and Andy Miller are joining Flex as part of the acquisition, the amount of which was not disclosed.

“They brought a lot of know-how around the actual design of the cup, but the Flex Company brought a lot of know-how around manufacturing,” Schulte said.

Flex will manufacture the Keela Cup and rename it the Flex Cup with slight changes to its manufacturing process, but no change to the end product. The Flex Cup will be manufactured in the United States, while Flex’s disposable menstrual discs are manufactured in Canada.

The key element of the Keela Cup’s design is a pull string—like that of a tampon—that makes the cup easier to use, including for people with disabilities. Hartman Adamé has Ehlers-Danlos syndrome, a connective tissue disorder, and started working on designing a reusable menstrual product she could use after that diagnosis.

That backstory is similar to Schulte’s, who started working on Flex’s menstrual disc after suffering from chronic yeast infections and being unable to find a period product that worked for her.

The Flex Cup, Schulte expects, will add a different customer base to Flex. To get customers interested in its two products, Flex will start selling a Flex Discovery Kit that comes with a cup and two discs. Flex aims to get the cup on retail stores this spring. Its discs already sell at CVS, Rite Aid, and Walgreens.

The company says it more than doubled its net revenue in 2018 and had an eight-digit annual run rate this year.

This is technically Flex’s second acquisition, since the startup acquired its own manufacturing line from Softdisc.

With its new funding, too, Flex plans to hire staff and work on growth and research and development.