The siren can detective human infrared and linking to alarm devices then make an reaction. 
Widely used at home security alarm system. 
The product is based on low power consumption and high reliability Z - Wave technology, 
that resist interference and temperature changing, fancy design and installation without wiring, easy-to-use. 
This products also can easy integrated with any others Z-Wave products, 
such as Door/ Window Sensor, Gas Sensor, PIR Sensor, Telephone Alarm Device, so on.