The four-car air-conditioned trains, which will be similar in appearance to the existing M200 series, are being ordered as part of the project to extend the metro 13.9km west from Ruohlahti to Matinkylä in Espoo. Each 90m-long train will accommodate 576 passengers with full-width gangways to allow free movement of passengers through the train. The trains will be equipped with a temporary driver's cab, which will be removed when the migration to driverless operation is complete.

HKL says that after comparing all of the offers, the CAF bid was the most affordable and the contract is due to be signed by the end of the year.

The first train will be delivered for trials in 2014, and all 20 sets will enter service in 2015-16.

The contract includes options for additional trains, which would expand the fleet for the proposed extensions west from Matinkylä to Kivenlahti and east to Sipoo.