The Series 65 Heat Detectors monitor temperature by using either a dual thermistor network or a single thermistor network (CS versions) which provides a voltage output proportional to the external air temperature.
| Sensor configuration | Horizontal optical bench housing infra-red emitter and sensor, arranged radially to detect forward scattered light. |
| Materials housing | Polycarbonate |
| Detection principle | Photo-electric light scattering |
| Product length | 42mm |
| Product diameter | 100mm |
| Weight | 99g |
| Colour | White |
| Finish | Gloss |