Review on 🔒 BITIWEND Wireless Door Sensor: 600ft Range, 58 Chimes, 5 Volume Levels - Perfect for Business/Office/Home/Store Security & Alert System (1Sensor+1Receiver) by Joshua Flake

We used to have a magnetic bell on our office door but the spring kept getting stuck and we worked for hours without ringing. Found this solution on Revain and it works great. The sensor is non-contact, so there's nothing to wear out, just a CR1632 battery that will eventually need replacing. They can have a gap of up to half an inch, which came in handy since our door moves a bit when it closes. We could not mount the sensors flush to each other. Everything but the standard beep annoyed me. Sounds a bit like a doorbell, but I'm getting used to it. It could be a little louder, but it works. You'll need to experiment with different receiver placements. UPDATE: A year later this still works with the original battery. Mounted on the front door, however, it cannot withstand negative temperatures. Last year we had a mild winter, but this year we're seeing the Minnesota norm of several days of high temperatures falling below freezing. It does not work anymore. I'm pretty sure the battery is the problem. He took out the button's battery, warmed it in his hands (it was VERY cold), and the bell worked a little again. This is the first issue we've encountered - hopefully temporary as we're going through the coldest time of the year. Not recommended for Siberia, Nunavut etc.