They are based on and very similar in appearance to the K4000 used on the low-platform routes of the Cologne Stadtbahn network.

The low floor section stretches between both the outer doors through the articulation (which rests on an unpowered bogie).

They operate from an overhead power supply at 750 V DC, and have a maximum speed of 80 km/h (50 mph).

[6][7] All 24 trams were refurbished between 2008 and 2009, which involved a deep clean of the interior, installation of new seat moquette and a new lime green, blue and white external livery.

[9][10] 2535 was officially named Stephen Parascandolo 1980 - 2007 in a special ceremony at Beckenham Junction on 20 October 2007, in honour of Stephen Parascandolo, a well known local tram enthusiast and webmaster of the "Unofficial Croydon Tramlink website" who died at the age of 26 in a car accident in Hitchin.

The Office of Rail Regulation (ORR) refused to comment on whether the derailed tram was fitted with laminated safety glass, claiming that it was unable to do so because of the RAIB's investigation.

[13] Bombardier did not respond to requests for information on the type of glass that could have been the cause of fatalities in this derailment.