The "Link" diesel multiple units have been produced by the Polish manufacturer Pesa since 2012. Due to their distinctive head shape they quickly became known under the nickname "Shark". The two-part version is designated as class 632 in Germany, the three-part version as class 633.

In addition to Deutsche Bahn, the Niederbarnimer Eisenbahn also operates vehicles of this type. Outside Germany, they are also in service in the Czech Republic and in various regions of Poland.