The last letter C means that each rolling stock of this model consists of 8 cars and runs with a maximum speed of 350 km/h (217 mph).Innovations include the body bolster, vibration damper, spring parameters, transmission ratio, widening the carbody and increasing the speed of the trainsets.[citation needed] On 28 September 2009, an additional 20 CRH3C sets was ordered by the Chinese MOR.[13] In March 2009, a new contract was signed with China Northern Railways (CNR) to supply 100 16-car trainsets for 39.2B RMB with delivery from October 2010 onwards.[18] The first CRH380BL set with series number CRH380B-6401L rolled off the production line and was unveiled to the public in September 2010. it was manufactured by Tangshan Railway Vehicle.The new trains were reported as being "too sensitive" and the subject of frequent breakdowns in stormy weather.[26][27] The first sets where unveiled for public service on 6 December 2017 on the Xi'an–Chengdu HSR which opened a few days later.[28] A prototype highspeed train being developed at CRRC Tangshan capable of cars in a trainset to be swapped out according to demand.