Abstract: A quick response trigger assembly for an automatic sprinkler head comprises an inherently unstable compression element positioned between the frame of the sprinkler body and sealing assembly. A thermal sensor surrounds the periphery of the compression element and includes at least one heat gathering element positioned a preselected distance from the compression element. The thermal sensor maintains the compression element in compression when the sprinkler head is in the non-activated condition. The presence of a heat gathering member spaced a preselected distance from the compression element increases the surface area through which conduction occurs, and thus, enables the trigger assembly to exhibit sufficient thermal sensitivity necessary to classify the sprinkler head as a quick response. Additionally, the thermal sensor is formed of two or more members which are substantially identical in configuration to thereby decrease manufacturing costs.