4 "Flirt 3" from StadlerRail for the Südostbahn (SOB) in multiple traction on a pantograph test run between Oberaach and Erlen, RABe 526 # 003, # 004, # 002 and # 001. The SOB ordered 5 of this trains, to reinforce the "Traverso" RABe 526.1 in the peak hours and for S-Bahn service.