|Maximum speed||205 km/h (127 mph)|
|Weight||187 t (184 long tons; 206 short tons)|
|Power output||2,240 kW (3,000 hp)|
|Electric system(s)||15 kV 16 2⁄3 Hz AC catenary|
|Current collection method||Pantograph|
|Track gauge||1,435 mm (4 ft 8 1⁄2 in) standard gauge|
X3 is an electric multiple unit train used by Arlanda Express on the airport rail link service between Stockholm Central Station and Stockholm-Arlanda Airport in Sweden. Alstom built seven of these four-train car units in Birmingham, which were delivered in 1998 and 1999. The X3 is part of the Coradia family, and can reach speeds up to 205 km/h.
The trains are painted grey with yellow ends with varying interior colors. The units use standard gauge tracks and are fed electricity at 15 kV 16 2⁄3 Hz AC like the rest of the Swedish railway network, but the trains use separate stations at Arlanda and dedicated tracks at Stockholm C; in both cases, the platforms are higher than at other stations in Sweden, allowing step-free access to the trains without the use of low floors.