Photoelectric detector detects the smoke by a couple of IR diodes. The detector works once connected to DC power directly. Operation Indicator flashing signifies detector working normally and Alarming Indicator on signifies detector alarming. Built-in a couple of output contact contact connect/disconnect after alarm. Power-down/Auto-reset when no smoke exiting nearby. Installing with mounting base.
https://vedardalarm.com/manual-or-auto-reset-wired-smoke-detector-relay-output-p-318