THIRDREALITY Zigbee Contact Sensor 2 Pack, Door and Window Sensor for Home Security and Smart Home Automation, Works with Build-in Zigbee Hub,hub Required.

Excellent. I have a mix of Sonoff and these, and the Sonoff ones often disconnect and are not easy to use. These always stay connected, have great battery life, and are easy to open and replace batteries. They are larger than some, but I haven't noticed and it's worth it.

As time goes on there are fewer and fewer things that impress me and actually improve how I interact with my smart home. Well today is a new day and color me impressed. These contact sensors work phenomenally. They work really fast with my SmartThings hub they paired automatically with the correct driver all I did was scan for a device. I was a bit worried as the correct device did not show up by selecting third reality from the add device list. I really like that it takes 2 AAA batteries as they are easily accessible. I have never thought that a contact sensor would be useful and preferred motion and presence sensors. However I installed these on the utility room door and a door to a walk-in closet. Both of which are not really big enough to close yourself in. These work perfectly open=on & closed=off. It's all ZigBee so virtually no lag by the time the door is open enough to walk through the lights are on. I'm a fan & I am thinking of ways to implement more.

These are really good. They work very reliably and hooked into the SmartThings ecosystem and my hub without any issues. It's Zigbee based so most Zigbee systems should be compatible but check first. Your milage may vary since the ecosystem and hub interoperability of smart home tech is a mess. The mounting and installation is easy and intuitive with the ridge to ridge contact points between the door and the frame needing to line up. Manual says the gap distance can be up to 16mm but I've found it supports a wider gap close to 25mm. Which is good. The only knock I have against these is the adhesive pads aren't great and if you try to position the two sensor parts too close together the air rush of the door swing can loosen them. Getting your own better adhesive pad and widening the gap slightly worked way better. Box does have screws included if you wanted to go that route to secure these to the frame and door but I didn't personally want to go that.

These Zigbee sensors work perfectly with SmartThings and have very low battery consumption. I've been using them for over 2 years without any issues. I highly recommend them!

Easily connected to an Echo 4th Gen smart speaker on first discovery scan from Alexa. Set up sensor on garage door and it reports open/close notifications almost immediately even though it’s not anywhere near the Echo speaker. I have a 1 1/4” gap between the sensor and its magnet and it still works flawlessly. It works much, much better than a wifi contact sensor. The only remaining thing to determine is just how long the AA batteries will actually last… Unfortunately, the battery status is not displayed in the Alexa app in the sensor’s information so I guess you have to wait for the battery to die and the sensor stops working before you know it’s time to change the battery…