Bests & Worsts Reviews from Amazon

These little things are great and they have a chime and alarm feature which is LOUD. Batteries come with it. The only thing is that I don't trust sticky tape or glue so I looked to see if there was a way to drill a small hole and screw them in - and there is, and I used my cheap drill press and a small bit big enough for a #4 stainless pan head sheet metal screw to fit through. The hole for the main unit can be where you take out the screw already there that holds the back to the front. (you can't see it unless you take off the battery cover for the 4 LR-44 batteries. On the magnet unit, only the top half of the little magnet unit that fixes to the door frame has the magnet. You can shine the thing under a bright light and see where it is. Just drill the other half. Get some #4 screws like I said (I used 1" and 1 1/4") and just mark the spots to drill on the door and frame with a thin scratch awl or tiny brad nail while holding it in position. Drill the wood and install the pieces and screw. They won't fall down next year in your basement when the tape finally gives way and the thing wakes you up in the middle of the night.