SHIELD Photo-Electric Smoke Detector works on the light-scatter principle and is ideal for applications where slow-burning or smoldering fires are likely. ■ Responds well to slow-burning, smoldering fires. ■ Well suited for bedrooms and escape routes. ■ Unaffected by atmospheric pressure Technical Data Detector Type : Photoelectric Working Voltage: 17 – 28 V DC Modulation Voltage:  5 – 9 V Maximum Alarm Current LED On : 4.5 mA Surge Current : 1.0 mA supervisory Current :340 μA Test Method: Home Safeguard, Gemini 501 Storage Temperature Range : -30°C to +80°C Operating Temperature Range -20°C to +60°C Dimensions (diameter x height) 100 mm x 42 mm Weight 105 g