An airflow module for being received in a module bay of a data storage device enclosure is disclosed. The airflow module comprises a body having: a first face having a first opening therein; a second face having a second opening therein, the first face being adjacent to the second face; and, an airflow channel between the first opening and the second opening so as to allow the passage of air between the first opening and the second opening. The first and second openings are arranged to co-operate with airflow openings in modules positioned in adjacent bays of a said data storage device enclosure to direct a cooling stream of air between said modules in use. The airflow channel is free from components that generate substantial amounts of heat in their normal operation.