I have an OPTEX wireless 1000 model RC-10U. I have used it for over 3 years and it does a very good job. I have it mounted on a fence post aimed at the drive way approx. 500 ft from the house. The only problem we have is the Deer sometimes set it off and a few times bees have set it off building a nest on the post under it. I change the battery in the remote end once a year when I do the smoke alarms. We find it very helpful just to let us know when company comes although since I have gotten my puppies (88 and 72 lb Labs) I find I really don't need the alarm like we once did.