A PCI card is inserted through an I/O opening in a computer panel. On one edge of the card is a cover from one end of which projects a tab. A resilient gasket is attached to the panel to create a flexible EMC seal around the opening. Preferably the gasket is formed of tin-plated beryllium copper. The gasket has alternate staggered spring fingers oriented opposite to the direction of insertion of the PCI card. To retain the gasket the panel is formed with slots at either end and an outward struck projection at the middle. The gasket is formed with a tongue at either end to be inserted in one of the slots and a punched-out opening to receive the projection.