Don't be caught unaware by unexpected visitors. The Wireless Motion Alert system will send an instant alert from the foot of your driveway to your home when a person or car enters your property. The weatherproof transmitter operates on one 9-volt battery (sold separately) and is easily mounted on a tree or post near the driveway (mounting materials sold separately). The transmitter uses a passive infrared (PIR) beam to detect people or vehicles to a distance of up to 80 feet, then sends a radio signal back to the receiver, which can be placed in your home up to 3000 feet away. The receiver plugs into a standard wall outlet and can be placed on a table or mounted on the wall (mounting materials sold separately). When the receiver gets a signal from the transmitter, one of four user-specified tones (Classical, Westminster Chime, Ding Dong, or Whistle) will sound for a few seconds. There is also a volume control, allowing you to set the sound to the desired level. Up to four different zones can be monitored by adding additional transmitters (sold separately). The transmitters can be programmed so they will each sound a different tone at the receiver. Extra receivers are also available to be purchased separately — put them in several rooms in your house, so you'll always know the instant someone steps onto your property. A Wireless Motion Alert system is also available with a driveway probe. Ideal for locations where there may be deer or other large animals that would cause false signals with a motion detecting system, this system includes a probe that's buried at the base of your driveway and sends a signal to the transmitter when a car is detected.