The IKV B'Err was the lead ship of the B'Err-class prison ship (a sub-class of the Vor'cha-class outfitted for prisoner accomodation) in service to the Klingon Defense Force in the 24th century. Among three other ships, the B'Err was assigned the task to ferry prisoners until the asteroid impacted. (RIS Bouteina: "Fury of the Prison Ships")