These instruments are different from ordinary recorders in that their scale contains some intervals that are a little wider or narrower (for example, "light" fourth and "half-high" sixth) than the tempered scale (the "normal" Western European scale that is used on the piano and other fixed-pitch instruments). The sjøfløyte/tussefløyte's scale does not follow a fixed pattern, and can vary from instrument to instrument.
The sjøfløyte (sea flute) probably got its name because it originally came to Norway from Germany by boat, probably in the 1700's. The sjøfløyte has also been called "city flute." It has been most common in Numedal, Telemark, Valdres and Hallingdal. The tussefløyte (also called "country flute"), is somewhat smaller and possibly more inspired by the baroque flute. It originated from the 1600's.