This motion-activated, infrared alarm requires no tools or wires and installs in seconds. Its many uses include: outside use to detect unwanted intruders, or inside use to monitor the wanderings of loved ones. The monitor can be placed up to 400 feet (122m) from the detection unit. Uses one 9V and 3 AA batteries (not included). Alarm loudness on low is 94dB and on high 106dB.