Abstract: A linkage element for releasing a mechanism under influence of temperature, such as a fire extinguishing sprinkler or ventilation shutter. The element must be capable of retaining a maximum bias force, but has also to show a short response time to excessive temperature conditions. The linkage element comprises a pair of coplanar flat jaws, opposite to each other and having a common base. The resistance to flexion in the plane of each jaw is high, whereas the resistance in a plane perpendicular thereto is low. The element further comprises a shape memory alloy, treated for moving the jaws apart from each other in a direction perpendicular to the plane of the jaws when the critical temperature is reached. The element is preferably made in the form of a small thin plate of shape memory alloy.