The BLS RABe 515, also known as MUTZ,^{[lower-alpha 1]} is a class of bilevel electric multiple units manufactured by Stadler Rail for BLS AG. It is a second-generation derivative of the Stadler KISS. Formations are composed of four or six cars. They were the first bilevel cars used by BLS.

BLS ordered 28 four-car trainsets in March 2010 at a cost of CHF 494 million. BLS planned to use the cars on various Bern S-Bahn routes.^[2] The first trains entered service on 19 September 2012.^[3] All 28 trains were in service by the December 2014 timetable change.^[4] BLS ordered three more trainsets in 2015, also for use on S-Bahn routes.^[5] In 2018, BLS exercised an option for eight more trainsets for use on long-distance routes between Bern and Biel/Bienne and Bern and Olten. Five of these use an extended six-car formation.^[6]

The four-car formation is 102,240 millimetres (335 ft 5+3⁄16 in) long. Cars stand 4,595 millimetres (15 ft 7⁄8 in) tall and are 2,800 millimetres (9 ft 2+1⁄4 in) wide. The four-car trains have seating for 335 passengers; the six-car trains can accommodate 546. The design speed is 160 kilometres per hour (99 mph).^[7][8]

In both formations there are cabs at the front and rear ends. The four-car formation has a single car with split first class and second class seating, with the six-car formation has two such cars. Passengers sit on both levels of the cars. The cars are low floor. Stairs at each end of each car permit access to the gangway between cars and to the upper level.^[9][10]

As of 2022^[update], the BLS RABe 515 is used on the S1, S3, S31, and S6 of the Bern S-Bahn, and on the Bern–Biel/Bienne and Bern–Olten InterRegio services.^[1]