The Surfwinteenagers launched into their well-rehearsed pitch in the exposed-brick loft of a Raleigh, North Carolina, co-working space. Two men, a venture capitalist and a lawyer, listened.

“The menstrual cycle occurs 450 times in a woman’s life. But we’ve yet to normalize it,” said Nandini Kanthi, 18. In many places, periods are taboo.

“But! What if we could turn the commonly stigmatized menstrual blood into a life-saving device?” said Shailen Fofaria, 15, the team’s only man. “What if you could make your period count?”