DF 303 - SD analogue addressable photoelectric smoke detectors are microprocessor controlled state- of-the-art detectors suitable for connection to addressable fire detection control and indicating equipment. Up to 254 detectors can be connected to each alarm zone loop. Advanced electronics in conjunction with a photoelectric smoke sensing chamber provide early detection of smoke and high immunity against unwanted alarms. The DF 303 - SD range of analogue addressable detectors provides fire detection and alarm system designers with a Standards-compliant, premium smoke detector for life safety and property protection applications.