THIRDREALITY Zigbee Contact Sensor 4 Pack, Door and Window Monitor, Home Automation,Works with Home Assistant,SmartThings,Aeotec,Homey,Hubitat or Echo Devices with Build-in Zigbee Hub,hub Required
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$75.98
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Availability:
In Stock.
Arrives
Tuesday, Nov 3
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At a glance
- Condition
- New
- Style
- Door Sensor 4 Pack
- Model
- 3RDS17BZ
- Dimensions
- 1.97 x 0.83 x 2.36 in
- Weight
- 0.29 kg
- Material
- Plastic
- Maximum Supply Voltage
- 3 V DC
- In the box
- Door Sensor × 4AAA Battery × 8Double-sided Tape × 4Screw × 8
Features 5
- ZIGBEE STANDARD COMPATIBLE DOOR SENSOR: Works with compatible Zigbee hubs or Echo devices with Zigbee hub built-in. Such as Echo (4th Gen), Echo Plus (1st Gen and 2nd Gen), Echo Studio, Eero 6, Eero Pro 6, Home Assistant, Home Assistant, SmartThings 2015/2018, Aeotec, Hubitat, Homey Bridge, Homey Pro, Third reality Hub and Third Reality Smart Speakers.
- HASSLE-FREE SETUP: Installs in a few seconds. Just make sure device in paring mode and compatible Echo device automatically discovers it by saying Alexa, discover devices.
- SUIT FOR MOSTLY DOORS AND WINDOWS OF THE HOUSE AND 2-YEARS LONG BATTERY LIFE: Door Sensor uses two AAA 1.5V Alkaline batteries for power, the batteries can last for up to 2 years and it is very easy to replace them. Note: Indoor use only and do not install the Door Sensor on metal door or window.
- MORE FUN WITH ALEXA ROUTINES: Using the Alexa app, create your own routines that are triggered When door or window is open, turn on a light, send an alert to your phone, let Alexa make a voice alarm or make a joke, etc.
- UPGRADED THIRD REALITY APP AND SKILL FUNCTIONS: Connected with Third Reality Hub/Speaker, you can check the battery level in the APP, then replace the batteries in time; history record is also open to the users, so you can know when the state of the movement has been detected and deal with it in time. Enabled Third Reality Skill in the Alexa APP, you will have a low battery warning by emails.
Description
Third Reality is dedicated to developing easy-to-use smart home technology, allowing more users to easily manage and automate home devices without specialized skills. Our products emphasize simple installation and user-friendly interfaces. Door and window sensor can directly work with compatible ECHO. You can monitor every door and windows in your home and create routines to send messages to your smartphone when the door or window is open. You also can create routines that are triggered by the on/off status of the door sensor. Safeguard your home when you are on business or vocation, it will automatically push instant notification to your smartphone immediately. In smartphone, you can see the history records of the smart door sensor. Using the Smart Bridge MZ1(Sold separately) and the 3R-Installer App, you can customize the delay time to suit your preferences. Using two AAA standard batteries, the batteries life can last for up to two years and very easy to replace. When you cooking in the kitchen, no more worrying about the baby will slip out of the safety fence. When you enjoy your voaction, no more worrying about someone will break in. No more worrying about parents living alone forgetting or repeating their medication.
Specs 20
| Brand | THIRDREALITY |
|---|---|
| Item dimensions L x W x H | 1.97 x 0.83 x 2.36 inches |
| Material | Plastic |
| Item Weight | 0.29 kg |
| Style | Door Sensor 4 Pack |
| Maximum Supply Voltage | 3 V DC |
| Measuring Range | Binary Open/Closed |
| Mounting Type | Door Mount |
| Output Type | Digital |
| Specific Uses For Product | Contact Sensor |
| Material Type | Plastic |
| Style Name | Door Sensor 4 Pack |
| Item Dimensions | 1.97 x 0.83 x 2.36 inches |
| Brand Name | THIRDREALITY |
| Model | 3RDS17BZ |
| Number of Items | 1 |
| Number of Packs | 4 |
| Manufacturer | Third Reality, Inc |
| Unit Count | 4 Count |
| Part Number | 3RDS17BZ |
No specs match.
Frequently asked questions
If you place your order now, the estimated arrival date for this product is:
Tuesday, Nov 3
Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
To initiate a return, please visit our Returns Center.
View our full returns policy here.
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Top Amazon Reviews
A bit big, but it's ThirdReality so it just works
Style: Door Sensor 4 Pack
These are great door/window sensors that have been super reliable for me so far. I was tired of a few other brands falling off my Zigbee network, so I went to trusty ThirdReality and haven't been disappointed. They are a bit bigger than alternatives, but that's because they pack a couple of AAA batteries which I expect to last a long time (given their record with other Zigbee devices). It's been several weeks and no battery issues so far; I would guess they'll last months or even years depending on usage. ThirdReality is also a Home Assistant partner, which means they actually test their stuff with Home Assistant and ZHA for their Zigbee stuff. It's perfectly compatible with my Sonoff Zigbee radio, as well as the Home Assistant ZBT-2 I recently switched to. They're a bit on the large size and not particularly pretty, but I don't think you could find a more reliable contact sensor for doors or windows (or drawers, or car chargers, or toilet lids… whatever you freaks are automating!) or a better value anywhere else. If you have the physical space, I'd highly recommend them!
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Reviewed in the United States on January 12, 2026 by Cassidy
Simple, Reliable, Power Efficient
Style: Door Sensor 4 Pack
I purchased these to help with various automations around the house including turning lights on and off, warning if freezer/refrigerator doors are left open, etc. and they work perfectly with my Home Assistant setup. The devices were instantly recognized by my Sonoff Zigbee 3.0 USB Dongle Plus (connected to my Pi5 running Home Assistant) and I could setup everything from there. So far, zero complaints as they work like a charm. For those folks frustrated with the mounting tape included with these such that upon removal the devices can crack, I simply used 3M Command Damage-Free Hanging Strips to make moving them super easy. Attached is a picture of the one I have installed atop the inside of my pantry door. I moved it from one spot to another using the Command strip and it came off damage free.
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Reviewed in the United States on December 14, 2025 by Scotchpb
My Mailbox Buddy
Style: Door Sensor 4 Pack
It’s been working as a mailbox sensor without any issues. This replaced my Wyze sensor that was in the mailbox. Now I have better home integration flexibility with Home Assistant. Armed for the mailbox bandit to strike again.
Reviewed in the United States on August 29, 2026 by Voice of the Public
Physically fragile technically great.
Style: Door Sensor 4 Pack
Functionally, these sensors are great. Just be aware they’re a bit fragile and really not designed to be removed once installed. The magnet portion, in particular, can crack if you take it off after mounting—I had to repaint my doors and removed three of them, and all three ended up with small cracks. Nothing a little super glue couldn’t fix, but still worth noting. After reinstalling, the gap between the magnets and the sensor ended up slightly too large, so the sensors occasionally reported the door as open even when it was fully shut. I resolved this by 3D-printing small risers shaped like the original magnet housing, and that fixed the issue. Despite these quirks, I’m still giving them five stars because I’ve had zero technical issues. They work reliably and do exactly what they should. Just know going in that they aren’t really meant to be reused. You’ve been warned.
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Reviewed in the United States on November 15, 2025 by Carl Porter
I wouldn't bother buying something more expensive, these are perfect
Style: Door Sensor 4 Pack
Cheap, simple, and functional. They pair easily to home assistant and are very responsive.
Reviewed in the United States on May 27, 2026 by IOI-655321
Good, but with one surprising caveat
Style: Door Sensor 4 Pack
Overall I’m pleased with these sensors. I like that they use AAA batteries Compatibility is fine - I haven’t had any issues with their connectivity (I use a mix of Zigbee vendor devices off a Sonoff Zigbee dongle). Detection range of the magnet is OK, but can be a little tight depending on this next factor: Something that is very strange about them is that the two parts of the sensor are not the same thickness. The main body is quite a bit thicker than the small magnet. This means that if you mount them on a level surface, they will not be level with each other! Depending on your situation, this can affect detection. A strange choice, but not a deal breaker for my use cases.
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Reviewed in the United States on January 20, 2026 by D. Neufeld
Does what it advertises without fuss
Style: Door Sensor 4 Pack
Great value for the money, and the simple AAA batteries (included) and long battery life make this a nice low maintenance way to keep track of if a door/window is open or closed. Unlike the Aeotec/Smart Things sensors, this does NOT track tilt/temperature/vibration, but on the flip side, the battery will last FAR longer then that sensor, and it doesn't use annoying coin based batteries which are far more expensive. Like everything made by this brand, it pairs into home assistant extremely easily and it 'just works'.
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Reviewed in the United States on February 17, 2026 by Matt E
Terrible products
Style: Door Sensor 4 Pack
Don't waste your money, or your time, on Third Reality products. No range, disconnect frequently, and chews up battery life. They're all just useless products. I bought several different sensors. Motion and contact. Difficult to pair, and then disconnect often. Seriously, just find a different product manufacturer.
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Reviewed in the United States on May 3, 2025 by Gregg G