Securityman MCYSM80, The Add-On Wireless Wide-Angle PIR (Passive Infra Red) Motion Sensor for Air-Alarm System by SecurityMan detects an infrared-emitting source with one temperature such as a human body that passes in front of a source with another temperature such as a wall. It does not detect non-temerature objects or real motion-it detects that something has broken the field which the sensor has determined as the "normal" state. The PIR sensor is set to detect rapid temperature change which means that it works in the cases of intrusion (Human) and fire. Add-on wireless motion sensor for SecurityMan Air-Alarm systemWireless transmitting distance: e450ft in open areaDetecting distance: 100 10 x 10mOperating power: 9V alkaline batteryBattery life up to 2 years
I've bought this Securityman Watches White Wireless Wide-angle Pir Motion Sensor For Air-alarm System for my sister. It's great gift for just 28.99.