I bought this because for some reason my garage door opener had an incredibly limited range. This unit has fixed this problem. I can open my garage from anywhere as long as I have a cell signal or am connected to a network. As other reviewers noted, it does take a few times to pair the devices. KEEP TRYING! I decided to screw the sensor unit on one of the garage door panel braces. It works great. I have a Samsung Galaxy S4 and have had no problems with the app.