The Sm5 electric multiple unit (EMU) is a low-floor train used on the Helsinki commuter rail network.

Unlike other train types on the network, the Sm5 units are owned by Pääkaupunkiseudun Junakalusto Oy, a subsidiary of the cities of Helsinki, Espoo, Vantaa and Kauniainen.

The units are leased to the Helsinki Regional Transport Authority (HSL), and VR operates them.

The entrance areas are fitted with fan heaters in order to preserve the interior climate as passengers enter and leave during cold weather.

The trains are transported from the Swiss factory by road and ferry, since they cannot run on European standard gauge railways.