According to the tender notice SOB requires six 150m-long inter-regional trains (type 1) and five 75m-long trains (type 2), which will be capable of operating in multiple with the longer trains. The type 2 trains will also need to be suitable for operation on suburban services. The contract will include options for an additional 14 type 1 and 15 type 2 sets, as well as up to 10 sets of a third type, which will be a 100-120m-long regional derivative of the type 1 train.

The fleet will enter service from 2019 and will be compliant with TSI PRM standards for passengers with reduced mobility.

Although the trains are only intended for use on the Swiss network, the tender document states that the trains may also need to be authorised for operation in Austria and Germany.

SOB plans to finance the order through its own resources. The closing date for expressions of interest is December 23.