A few of the fifteen major types of electric powered plugs in use world wide. Letters are assigned by the U.S. Department of Commerce and they are for identification only. Worldstandards.eu, CC BY-ND To understand why electric outlets aren’t all a similar, you have to know how a plug operates. https://types-of-microphones-in-r63840.blogoscience.com/35453886/not-known-factual-statements-about-different-types-of-male-electrical-plugs