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4. Heidi Zak and Ra’el Cohen, ThirdLove

Heidi Zak was fed up with uncomfortable, unsupportive bras, so she decided to build her own. Teaming up with bra designer Ra’el Cohen, Zak left her job at Google and in 2013, they launched ThirdLove, selling bras based not just on breast size, but also on shape, and offering half-cup sizes.

ThirdLove tests its bras on real women rather than fit models and now sells bras in 78 sizes. The company partners with I Support the Girls, which supports women going through difficult transitions; last year, ThirdLove donated $10 million worth of bras to women in need.