The AN/99ST Intrusion Detection Alarm System provides effective and affordable home security. Whenever any vehicle, intruder, or even an expected guest approaches your property, this perimeter intrusion detection system alerts you to their arrival. It is simple to operate yet technically sophisticated, and is completely wireless. It's ideal for monitoring your driveway, yard, house, etc. The system consists of two basic components: an infra-red sensor/transmitter unit and a receiver/alarm unit. The sensor detects the presence of a vehicle or person through heat and motion, and then immediately transmits via a 300 MHz radio signal to the receiver in the house which sounds the alarm. It has an exceptional range of up to 1500 ft. The sensor/transmitter unit is a special military version. It's green in color to blend in discreetly in outdoor installations. It's weatherproof, includes mounting hardware, operates in temperatures down to minus 40-degree F, and meets Mil Standard 2000. It mounts easily on a tree or fence, in the garage, at a pool entrance, or anywhere security is desired. The sensor has an adjustable 20-degree x 40-degree field of view with a 30 ft detection zone and is powered by a 9-volt battery (included), which can last over a year since the unit draws just .05 milliamps. The receiver/alarm unit is plugged into a standard electrical outlet inside your house. Upon receipt of the alarm transmission from the sensor unit, the receiver unit sounds its alarm for 6 seconds and illuminates its LED light, and then resets itself. (The LED remains illuminated until you manually re-set it, so you'll know if there's been an intrusion while you were away.) The receiver has a volume control for the alarm. Size: 3" x 4.25" x 1.5" (sensor), 4.25" x 3.25" x 1" (receiver). The standard system we sell consists of one sensor and one receiver, but as many additional sensor units and receiver units may be added as required to customize your system since all are compatible with each other. Additional sensor and receiver units are sold separately. Made in U.S.A.