When the water temperature is higher, the resistance value is lower. The lower the water temperature, the greater the resistance value. Working range: 0-120 degrees. Alarm temperature: 97 + -2 degrees When the water temperature reaches the alarm temperature and the alarm switch is closed, the alarm light will turn on. When the water temperature decreases and the alarm switch is turned off, the alarm light will be turned off. When the alarm temperature is reached, the response time is approximately 1 second. The water temperature sensor has 2 wires, one is connected to the water temperature meter, and the water temperature parameter is displayed. The other one is connected alarm switch application: crude oil engine colour:Golden Material:metal size:21mm Package Contents: 1 x water temperature sensor Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.