The detectors are photo-electronic detector uses a state of-the-art optical sensing chamber. This detector is designed to provide open area protection and to be used with most security alarm control panel. Two LEDs on each detector provide local 360° visible alarm indication. They flash every 5-6 seconds indicating that power is applied and the detector is working properly. The LEDs latch on in alarm，will be off when a trouble condition exists indicating that the detector sensitivity is outside the listed limit. Heat detector and smoke & heat detector combine a photo electronic sensing chamber and a temperature heat detector.