Mary Beatrice Davidson Kenner was an African American inventor most noted for her development of The sanitary belt with a moisture-proof napkin pocket. 

The company who was initially interested in the belt rejected it when they learned that Kenner was black, so her useful invention wasn’t patented until thirty years later. 

In 1957 she was able to save up enough money to get a patent on it. Until that time, tampons were available but were considered indecent, so women commonly used cloth or rags for protection—or just stayed indoors during their period.

This invention of Mary Beatrice Davidson Kenner gave women more freedom during their time of the month.