True, they're not part of the Euro zone. They're part of the Schengen area (common immigration zone), the EFTA (free trade area), signed the EEA, and adopted by themselves most EU regulations. [1] While not an ECJ member, they are softening their stance on that also [2].
[1] https://theconversation.com/what-is-the-swiss-model-of-co-op...
[2] https://www.ft.com/content/17d840b6-209b-11e8-a895-1ba1f72c2...