eufy Security Entry Sensor, Detects Opened and Closed Doors or Windows
Quick take
The eufy Security Entry Sensor is a compact contact sensor that detects when doors or windows open and close, and then alerts your smartphone through a compatible eufy HomeBase. It can also trigger a 100-decibel siren via the HomeBase, and the included battery is rated for up to 2 years of monitoring. The biggest limitation is that it requires the eufy HomeBase to function, so it is best for people who already use (or plan to use) the eufy alarm ecosystem.
Pros and cons
Pros
- Designed for door and window contact monitoring, using a magnet to detect open versus closed status.
- Up to 800 days (about 2 years) of monitoring per included battery.
- Can trigger a 100-decibel siren on the HomeBase, and supports smartphone alerts.
- Supports optional 24/7 professional monitoring when triggered (service availability depends on enrollment).
Cons
- Requires eufy Security HomeBase, so it cannot operate as a standalone sensor.
- Buyer feedback points to app- and feature-workflow gaps, including limited smart home integration and fewer “chime” style experiences.
- Mounting can be hit-or-miss on porous or uneven door/window frames, sometimes requiring screws instead of adhesive.
What buyers think
Buyer review evidence is generally positive on core functionality and reliability. People commonly describe easy synchronization with a compatible eufy HomeBase and consistent tracking of door open-close status. Several buyers also highlight that the siren and smartphone notifications can be used effectively when the system is armed, and that the sensor can be added to an existing eufy setup without major hassle.
Where feedback gets more mixed is around the software experience. Some buyers feel the app workflow can be less convenient than they want for everyday arming and disarming, and they mention missing or limited integrations with other smart home platforms. A smaller theme also shows up around physical mounting, where the adhesive may not hold as well on certain door frame surfaces, and the magnet assembly or screw mounting can feel less robust than expected.
Overall, buyer-review evidence suggests the sensor performs its primary job well when paired with the right HomeBase, but the “whole experience” depends heavily on the eufy app workflow and your door/window mounting surface.
What it is and how it works
This is a battery-powered contact sensor meant for doors and windows. The sensor unit installs on the moving part (like a door), while the magnet mounts opposite it. When the door or window opens, the sensor detects the separation and reports the open event to your eufy HomeBase, which can then alert your phone and, when configured, trigger the HomeBase siren.
Battery life and power expectations
The included CR123A battery is specified for up to 800 days of monitoring. That long runtime is a big deal for contact sensors, since they are meant to be installed and forgotten rather than constantly recharged. If you are adding multiple entry points, the “set it and maintain it less often” angle is a key reason buyers consider this kind of sensor.
Alerts, siren, and optional 24/7 monitoring
When the system is armed, the sensor can send an alert to your smartphone when a forced open is detected, and it can trigger a 100-decibel siren through the HomeBase. There is also an optional 24/7 protection service mentioned for emergency police, fire, and medical response when your alarm system is triggered. If you are comparing options, the practical takeaway is that the siren and professional monitoring capabilities are tied to the HomeBase and the service setup, not just the sensor itself.
Setup and mounting: what to plan for
Installation is straightforward for many standard door and window setups, and the kit includes the entry sensor, magnet, a CR123A battery, and mounting hardware (screws plus an owner’s manual). Still, mounting is where real-world differences show up.
Some buyers report that adhesive mounting works well on smooth surfaces, but on porous or uneven door/window frames, adhesive may not hold strongly enough. If your frames are rough or textured, plan on using the included screws or be ready to supplement the mount to keep the magnet aligned. Misalignment can cause missed events or inconsistent detection, so it is worth taking your time on positioning.
App experience and smart home expectations
Because this sensor relies on the eufy HomeBase and app, daily usability depends on how you want to arm, disarm, and receive notifications. Feedback includes concerns that the app can require multiple taps for everyday actions and that some smart home integrations some people expect are not present (or are limited). If you are choosing this sensor mainly for automation with other platforms or voice assistants, confirm your preferred integration path first.
Who this is best for
- You already own a eufy Security HomeBase (or you are actively building a eufy alarm setup) and want to add door/window monitoring.
- You want alerts and the ability to trigger a siren when the system is armed, with a battery life designed for long intervals.
- Your door and window frames can support stable sensor placement, either via adhesive on smooth surfaces or screws on rougher ones.
Who should consider a different option
- You want a standalone sensor that works without a HomeBase.
- You need frequent daily “chime” style feedback when doors open (especially when the system is not armed), or you want a smoother arm/disarm experience than the current app workflow provides.
- You require tight integration with other smart home ecosystems or specific automation routines, and you want to avoid potential compatibility gaps.
Pros and cons summary
- Best part: dependable contact monitoring for door/window openings with long battery life and siren/alert support through HomeBase.
- Main tradeoff: the sensor’s usefulness depends on having and configuring the HomeBase, and the app experience can be less convenient than some buyers want.
- Mounting reality check: adhesive works great on suitable surfaces, but rough or porous frames may need screws or extra support for stable alignment.
Verdict
The eufy Security Entry Sensor is a solid choice if you are expanding an existing eufy HomeBase alarm setup and want reliable door and window contact monitoring. It offers long battery life, smartphone alerts, and the ability to trigger a 100-decibel siren through the HomeBase. Just be sure you are comfortable with the HomeBase requirement and that the app workflow and smart home integration options match your expectations.
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FAQs
Does the eufy entry sensor work without a HomeBase?
No. This sensor is designed to work with a compatible eufy Security HomeBase, which handles alerts and can trigger the HomeBase siren.
How long does the battery last?
The included CR123A battery is rated for up to 800 days (about 2 years) of monitoring.
Can it trigger a siren?
Yes, the sensor can trigger a 100-decibel siren through the HomeBase when configured and when forced entry is detected.
What doors or windows can it be mounted on?
It is designed for doors and windows and mounts using the included screws and/or adhesive support, with placement that keeps the magnet and sensor aligned.
Is it for indoor use only?
Yes, it is intended for indoor use only.
Specifications
| Product Title | eufy Security Entry Sensor, Detects Opened and Closed Doors or Windows, Door Monitoring, Sends Alerts, Triggers Siren, 2-Year Battery Life, Indoor Use Only, Requires HomeBase, 24/7 Monitoring Optional |
|---|---|
| Category | Electronics > Security & Surveillance > Home Security Systems |
| Brand | eufy Security |
| Manufacturer | eufy security |
| Model Number | T8900 |
| Color | white |
| Size | 1 Count (Pack of 1) |
| Item Weight | 0.15 Pounds |
| Product Dimensions | 1.1"L x 0.87"W x 2.91"H |
| Power Source | Battery Powered |
| Compatible Devices | Smartphone |
| Battery Description | Lithium |
| Number of Batteries | 1 Lithium Ion batteries required. (included) |
| Control Method | App |
| Audible Noise | 100 Decibels |
| Mounting Type | Door Mount, Window Mount |
| Sensor Technology | Contact Sensor |
| Wattage | 7.5 watts |
| Smart Home Compatibility | Smart Home Compatible |
| Item Dimensions L x W x H | 1.1"L x 0.87"W x 2.91"H |
| EU Spare Part Availability Duration | 2 Years |
| UPC | 848061058666 |
| Global Trade Identification Number | 00848061058666 |
| Manufacturer Warranty Description | 12-month warranty and provide friendly, easy-to-reach support. |
| Mfr Part Number | AK-848061058666 |
| Unit Count | 1.0 Count |
| Built-In Media | Entry Sensor, CR123A Battery, Magnet, 3 x Mounting Screws, Owner's Manual, Happy Card. |
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