The Bosch Blue Line Gen2 Quad PIR Detector uses two individual sensors that operate like two PIRs in one detector. Each sensor processes signals separately however both must activate to generate an alarm signal. This improves false alarm immunity relative to a standard PIR, because false alarm sources such as noise spikes and small animals are ignored. Quad detectors also provide superior catch performance versus a standard PIR or dual-technology detector and are particularly well suited for challenging installation situations; for example, cases where cross catch of intruders cannot be guaranteed or where intruders are able to cross the detection pattern very quickly.