There is provided a door or side panel for a cabinet for storing data processing or telecommunications equipment, the door or side panel comprising a first vertical face and an opposing second vertical face, a first vertical side and an opposing second vertical side, and a first horizontal side and an opposing second horizontal side; the door or side panel further comprising at least one partition means positioned between the first and second vertical faces, and also comprising at least one air passage arranged so that air may pass through the door or side panel from the first vertical face, past the partition means, to the second vertical face, or from the second vertical face, past the partition means, to the first vertical face. There is also provided a cabinet for storing data processing or telecommunications equipment comprising one or more door or side panels of the invention.