MaxWorks 70899 Wireless Long Range Security Motion Sensor with Home Base High/Low Volume 3 Chime Indicator, Small, White When the infrared sensor identifies movement from cars or people, the sensor will send a wireless signal to home base causing it to play alerting sounds Detection of movement can be reached to about 18 feet and also a 300 feet signal transmission from home base to sensor Could be used to deter intruders or as simple as detecting when someone is at the door. Also could be used for stores to notify that there are customers Simple installation no wiring. Requires one 9 volt battery for sensor & 3- 1.5 volt battery for home base which are not included. The DC cord for the home base is optional & is sold separately A great solution to maximize security detection at a low cost not to mention no monthly recurring fees. Home base receiver has built in high and low three chime settings