Abstract: A computer casing includes a side panel releasably attached thereto for covering an opening defined in a side wall thereof. The side panel has a first edge from which a perpendicular flange extends. Anchoring tabs perpendicularly extend from the flange. A step is formed on a corresponding edge of the opening with slots defined therein to receive the anchoring tabs with the flange abutting against the step thereby effectively eliminating electromagnetic radiation emitted through the opening. A plurality of locking tabs are formed on an opposite second edge of the side panel. Cutouts are defined in a rear wall of the casing corresponding to the locking tabs. A locking rod movably attached to a rear wall defines a plurality of openings corresponding to the cutouts whereby the locking tabs are allowed to extend through both the cutouts of the casing and the openings of the locking rod when the locking rod is at an unlocked position.