The Series 65 Ionisation Smoke Detector uses a low activity radioactive foil to detect fires by irradiating the air in the smoke chambers and causing a current flow. If smoke enters the chamber, the current flow is reduced leading to an alarm.
Approvals: AS 7240.7-2004

| Voltage | 9-33 VDC |
| Quiescent Current | 20-45µA at 24 VDC |
| Alarm Current | 52mA at 24 VDC |
| Operating Temperature | -20°C to +60°C (no icing) |
| Relative Humidity | 0% to 95% (non condensing) |
| IP Rating | IP23D (EN60529) |
| Size (inc Base) | 100mm Dia x 50mm H |
| Weight (inc Base) | 153 grams |
| 4106-1002 | Series 65 Ionisation Smoke Detector |