The "part6.rar" designation indicates this is the sixth segment of a larger file. To access the content:
The "Back to Hell" expansion introduces significant new gameplay elements and historical content: Steel.Division.Normandy.44.Back.to.Hell.part6.rar
: You must have all parts (e.g., part1, part2, ..., part6) in the same folder for the extraction to work. The "part6
: Features veteran British desert units. Steel.Division.Normandy.44.Back.to.Hell.part6.rar