What is "silberling"

Silberling is the colloquial name for the n-coaches of the Deutsche Bundesbahn, a type of regional passenger coach of which more than 7,000 units were built from 1958 to 1981. Nearly all of the coaches have undergone extensive modernisation – these modernised units are widely known as Mintling, Grünling ("greenling") or Rotling ("redling") after their exterior colours. The term Buntling ("colourfulling") is used to denote refurbished Silberling coaches in general.