Don't get caught by surprise.  This motion-activated alarm detects movement in a 140 degree wide, 60' zone.  The motion sensor triggers a response in the receiver, automatically turning on whatever device you have plugged into the device's buit-in outlet. Includes sensor, receiver and 1 12V battery.  Wireless.  140 degree X 60' detection zone.  On/off switch for alarm on receiver.  Works day and night.  Requires 4 AA batteries, not included.  Measurements:  3-1/4"WX3"HX3"D; Receiver 4"LX2-1/2"W.  FCC compliant.  One-year limited Manufacturer's warranty.  Made in China.