A firm order for Stadler to supply Schweizerische Südostbahn with a further 12 Flirt electric multiple-units was signed in St Gallen. The latest option to be exercised covers seven eight-car Flirt Traverso long-distance units with a copper-coloured livery, and five four-car silver-coloured Flirt regional EMUs.

SOB ordered an initial six eight-car and five four-car EMUs in June 2016, and in December 2017 exercised a first option for 11 more eight-car units. SOB will operate the Traverso sets on the Voralpen-Express route between St Gallen and Luzern from December 2019, on Gotthard mountain route from December 13 2020, and between Chur, Zürich and Bern from December 2021.