The British Rail Class 373 or TGV TMST, sometimes referred to as Eurostar e300, is a French designed and built electric multiple unit train that is used for Eurostar international high-speed rail services from the United Kingdom to France and Belgium through the Channel Tunnel. Part of the TGV family, it was built with a smaller cross-section to fit the smaller loading gauge in Britain, was originally capable of operating on the UK third rail network, and has extensive fireproofing in case of fire in the tunnel. It is both the second longest—387 metres (1,270 ft)—and second fastest train in regular UK passenger service, operating at speeds of up to 300 kilometres per hour (186 mph).