The receiving set driveway alarm you when a vehicle enters or exits your property. When a vehicle passes the sensor, the inside receiver a chime. It a receiving set range of 400 ' -LRB- 121.9 m -RRB- and will not be activated by people, animals or wind. The inside receiver can be on a table or on the wall. triple inside receivers -LRB- up to 3 -RRB- can be for more convenience. moving vehicles ; not a motion sensor.