Refurbishment
From April 2007 to 2008, all of the 9000 and 9050 series sets except prototype set 9101 underwent refurbishment ahead of introduction on Tokyo Metro Fukutoshin Line inter-running services from June 2008. Refurbishment included totally new interiors and cabs based on the 50070 series design. Externally, single-arm pantographs were fitted, and the destination indicator blinds replaced with full-colour LED displays. Prototype set 9101 was not refurbished due to the different door spacing of this set, making it incompatible with the platform doors on the Fukutoshin Line. This set is restricted to Tōbu Tōjō Line overground duties.
Read more about this topic: Tobu 9000 Series