This additional transmitter is for use with the STI-34150 battery-operated Wireless Driveway Monitor. It uses a patented magnetometer sensor system. Movement of any large metallic (iron or steel) object close to the driveway sensor will cause the sensor to transmit to the receiver.
Under ideal conditions, the sensor may be placed as far as 800 feet away from the receiver in your home. For the best performance, place the sensor within 500 feet of the receiver.