Excessive shock and vibration is common in computing platforms deployed in harsh environments across a range of defense and industrial applications. Also systems with limited or no airflow and containing high wattage board payloads are expected to operate with high reliability in extreme ambient temperatures every day. Elma’s SureLock family of card edge retainers are multi-segment, extruded aluminum retaining devices that secure printed circuit boards in place when mounted directly to the board and slid into a channel in the cold plate. A simple turn of a screw enables the SureLock to expand and securely hold the card assembly in place to ensure high, evenly distributed clamping forces over the length of the retainer. This provides solid mechanical rigidity while the consistent surface to surface contact ensures maximum heat transfer. The design facilitates conduction cooling by conducting heat from a circuit card to a cold plate or the extruded side walls of an enclosure.