This plug/outlet is technically known as the SEV 1011 (Swiss 10 A/250 V).

It was developed by Switzerland as its own standard, described in SEV 1011 (ASE1011/1959 SW10A-R). This plug is similar to the Type C europlug (CEE 7/16), except that it has an earth pin off to one side. Swiss sockets can take Swiss plugs or europlugs (CEE 7/16). This connector system is rated for up to 10 amperes. There is also a less common variant with 3 square pins rated for 16 A. Above 16 A, equipment must either be wired permanently to the electrical supply system with appropriate branch circuit protection, or connected to the mains with an appropriate high power industrial connector.

Switzerland also has a two-pin plug, with the same pin shape, size and spacing as the SEV 1011's live and neutral pins, but with a more flattened hexagonal form. It fits into both Swiss sockets (round and hexagonal) and CEE 7/16 sockets, and is rated for up to 10 A.