Honeywell Silent Knight 302-135 | 135 F (57 C) Vertical Mount.

302 Series rate-anticipation heat detectors operate within a controlled range of two to three degrees of their setpoints, regardless of the rate of temperature rise. These detectors are available in either 135 °F (57.2 °C) or 194 °F (90 °C) ratings. The 302 Series are normally open (NO) devices designed especially for fire detection and alarm systems. They respond and activate the fire alarm as soon as the temperature reaches the pre-set threshold setting. Under rapid heat rise conditions, the rate-anticipation feature enables the detector to respond one to three degrees ahead of the setting. At the same time however, they do not respond to momentary temperature fluctuations below the selected protection level, thus eliminating false alarms. When temperatures drop back down below the protection level, the detectors automatically resets itself.