TYPE F
Type F is used, for instance, in Germany, Austria, the Netherlands, Sweden, Finland, Norway, Portugal, Spain and Eastern Europe. (Click here for the full list of all countries that use type F)
Plug F is known as CEE 7/4 and commonly called “Schuko plug”, which is the acronym of “Schutzkontakt”, a German word meaning “protection contact” or “safety contact”. The plug was designed in Germany shortly after the First World War. It goes back to a patent (DE 370538) granted in 1926 to Albert Büttner, a Bavarian manufacturer of electrical accessories.
Type F is similar to C except that it is round and has the addition of top and bottom indentations with conductive clips in them in order to earth the appliance. The plug is not perfectly round, but has a pair of plastic notches on the left and right side to provide extra stability when using large and heavy plugs (e.g. with built-in transformers).