Inventions of the 20th century.

One of the first inventions of the 20th century was the double edged, disposable safety razor blade. Invented by King Camp Gillette who founded the Gillette Company in 1901 in Wisconsin USA, Gillette was granted two patents on razors, blades, and the combination of the two in 1904.
It eventually replaced the potentially lethal "cut throat" razor and was probably responsible for saving lives as well as providing a smoother easier shave and putting some barbers out of business!
It was the first type of razor that I used upon "becoming a man" in the 1960s  -  truly cutting edge technology ;-)

Thanks to laurie54 for hosting another intriguing MonoMonday.