Two radiation sources necessary for alarm. Minimize false alarm eventsField of view of up to 120 degrees .Wider coverage per detector. Explosion-proof, Class I, Division 1 certified. Suitable hazardous locations. FM certified to Performance Standard 3260. Engineered to the highest standards. Connect indoors or out, directly or up to 2000 feet away .Flexible installation. Immune lightning, arc welding, sunlight and hot body radiation. Limits false alarms caused by nearby activities. Adjustable, no-tool swivel mount. Simplifies installation and alignment. User programmable sensitivity and time delay settings. Adapt to different locations, conditions and activities. Multi-coloured, high intensity LEDs. See detector status in the field. Manual and automatic testing of optical surfaces. Allows maintenance scheduling by evaluating cleanliness. Watchdog timer monitors internal electronics. Continuous system self-diagnosis. Multiple output configurations available Connect a wide variety of equipment.