I have been using this alarm for years now. It is very reliable. The sensor/transmitter at the gate runs off lithium AA batteries and lasts for a year or more. My gate is about 400' from the house. You can also have multiple sensors that invoke a different sound so you and know from where the intrusion is coming. I have more than one. I also have a second system I utilize while hunting sometimes. If I'm in the box blind I put sensors in a couple of places that will give me a 'heads up' something is approaching thereby waking me from my nap.
