This is a Water Temperature Sensor (flow sensor) Probe M10 Screw with 1m (3.3ft) cable and temperature range of -58 to 230 °F (-50 to 110°C) that is compatible with some Hot tub sensors (the screw size is M10, so please check the sensor size before buying) This water proof sensor has a wide range of application but before buying, please check the dimensions and specifications on picture and following table that you select suitable sensor for your application.