Choosing a door/window sensor was aggravating to me. All the products seemed like either cheap junk or was a part of a larger system I had no need for. All I wanted was a product that makes a sound at a distant location whenever the door was opened. The reviews on this were mixed. The reality is that they do the job just fine. I like them. Can't beat the priceBIGGEST DRAWBACK: sensors require a special battery I can almost guarantee that you don't have. The batteries that COME WITH the sensors may not last long, but once they do and you buy a quality replacement, like duracell or energizer, they will last just fine. Maybe I'll be changing the batteries once a year. Nonetheless the fact that they take an odd size battery is inconvenient, but inconvenient in 2023 is generally not that inconvenient.Second biggest drawback: There is a minor design flaw. You shift the cover across the base to expose the battery. If you install it upside down (that is to say you would shift the cover down to remove from the base) you can have an issue where it falls off the door when its slammed or if you have a very heavy use door AND the installation configuration necessitates installing the sensor portion holding the battery on the door itself. I imagine this would never be a problem if you installed the sensor portion on the door frame, which if you can, I'd recommend. If its on the door try to make sure that the cover does not slide downwards in the installed location.TIP: keep in mind the angle configurations you're working with. You have two pieces, the sensor and the magnet. They have to face each other to activate the sensor in the closed position. If you have the sensor on the door and there is no room on the doorjamb to place the magnet in alignment with sensor, you will have to chisel out a chunk of the jamb (had to do this on one door). The door is obviously flat and one piece will be attached to the door. There needs to be a flat spot opposite the sensor to attach the magnet to. Look at your doors and figure out your angles to see if these are a good fit.SOUNDS: A lot of comments on the sounds almost convinced me to steer away. Its is slightly hilarious and ridiculous clicking through the doorbell sounds. Some are very long. Having options like Fur Elise and Ragtime is just hilarious. Imagine hearing a MIDI big band song for 20 seconds every time the door is opened (lol). That said, there are a solid 5-7 very normal and simple chimes, you just have to scroll through and find them and that's an entertaining time I assure you. These full-on songs are so unnecessary and hilarious.MULTIPLE ENTRIES: The nice bit is that you can use different chimes for different doors, so when the door opens you know which door opened even though it won't be a voice that says "Front Door.... open" like some integrated systems do.