SONOFF DW2 Wi-Fi Wireless Door Window Sensor,APP Alert for Home Automation Wireless Alarm Security System, Compatible with IFTTT, No Gateway Required.

Very good product. The only con I find is that it's not rechargeable and you need to replace the batteries.

Excelente

This product is useless. Does not work in modern networks. I was able to pair the two units, but they never connected to the ewelink network. There are lot's of complains about this (which sadly I did not read before purchasing). I had several Sonoff products and work fine. This should not be selling at all. Don't waste your time and money.

First, I'm not using this as a door sensor. I wanted it as an out-call notification when my alarm panel is activated. Located at a rural cabin, the alarm panel drives a siren so used that output through a relay to activate this sensor, which in turn provides a push notification to my phone. It did not pair up like my other Sonoff switches, but found that the bluetooth pairing option went smoothly and quickly. At this point, it does everything I wanted it to do - just hope it has longevity I also substituted a 3 vdc power supply for the batteries so I can't properly assess battery life, but none of that would apply to its expected use as a door/ window sensor. I did play with it using the included magnet, as well as other magnets, and the greatest sensitivity appears to be above and below the alignment mark on the sensor - nearer the ends of the reed switch inside the sensor. The included magnet also needs to be in very close proximity to the sensor - minimal spacing - and that could be an issue in actual application. If I were using this as a door sensor, and couldn't obtain the minimum spacing required for consistent holding and triggering, I would probably substitute a stronger magnet. I tried various combinations of rare-earth disc magnets made for fridge clips, and found I had a much better range of sensitivity without the need to keep spacing so close - and once the door opens, any field effect is gone and you still get a trigger. Get past the pairing and it should do the job.

I use it in the mailbox in our front yard. I was concerned that the WiFi range would be an issue but the signal strength is very good. The batteries are AAA. So replacing them is affordable.I use it in Home Assistant to notify us when we have mail. It is 100% reliable for us. Highly recommend it.

I make sure to have a Wifi 2.4GHz, Try all possible ways to pair it, and hasn't been possible, not exact support for error 6315, and description on manufacturer user manual is too general, it says check your user manual, but it says nothing.I have other Smart devices from the same brand and they paired immediately and work perfect, but this DW2 was about to throw it to the trash but in a forum I read besides to have 2.4GHz wifi network, its protocol have to support 'b', then once I did that config (by default it was G/N) to add the b protocol immediately I was able to pair and use.About the ITEAD support is a waste of time to read it, it says nothing, just make sure you have 2.4GHz Wifi and b protocol on it.I'll test it for a few days, and maybe update my general qualification.

Sonoff is easy to install and has a great phone app. I attached this to my garage door, and I get a "bing" on my phone when the door opens and closes. Amazon uses Key delivery to place items in my garage, so I know that they've been there and not to drive over the box that they left. That actually happened once. I know when my wife gets home. Very useful, easy to install. It also tells you when the battery is low.We've hacked it to allow a switch to activate it, controlling it with an electromagnet.

These are great. They’re smaller than I thought they’d be, stick well even after having to be moved a couple of times to get the alignment right, and have so far held their charge better than another brand I was using before. All that and their native app is my preferred, though it would be easy to flash them if you so desired. My only ask would be for them to make one with a way to connect an external sensor. This one would not be easy to modify in that way.