Finally the Card Loks and Wedge Loks which, within Schroff’s retainer product portfolio, provide the best performance both in terms of clamping force and thermal transfer. Birtcher Wedge Loks and Calmark Card Loks are designed specifically for cold wall applications, within rugged heavy shock vibration environments. The primary purpose for a Wedge Lok is for board retention, and the secondary purpose is heat transfer via conduction. Standard products are available in three or five segments, can be either screw or lever actuated, and provide consistently repeatable clamping forces despite supporting various PCB thicknesses. These Wedge Loks are ideal for many rugged applications, but are often found in Military and Defense systems such as tactical aircraft, UAV Control, fire control systems, helicopters, and tactical vehicles.