The OPAL and OPAL Plus incorporate PIR and MW technologies. The dual technology, combined with the algorithm of detector auto-adaptation to environmental conditions, ensures high immunity to false alarms and, consequently, stable operation in harsh weather conditions, such as rain, snow, sunshine and strong gusts of air. The ambient temperature changes are automatically compensated. Resistance of the detectors to extreme weather conditions have been confirmed by long-term tests. The devices offer correct operation within a wide temperature range from -40°C to +55°C.