Quick summary: SONOFF put the SenseGuard DW Gen3 door and window sensor on sale on 10 November 2026. The SNZT-04P can operate either as a Matter-over-Thread sensor or as a Zigbee 3.0 device, costs £20.88 including tax in SONOFF’s UK store and uses two replaceable AAA batteries. The choice is not simultaneous: changing radio modes factory-resets the sensor, and its tamper status is unavailable in Thread mode.
One sensor, two separate radio modes
SenseGuard DW Gen3 is a two-part magnetic contact sensor for doors and windows. SONOFF identifies the controller as a TL3238 rather than an Espressif chip, while the wireless specification lists IEEE 802.15.4 with Zigbee 3.0 and Thread support. It starts in Thread mode after first power-up; five button presses switch it to Zigbee.
| Feature | Verified detail |
|---|---|
| Model | SNZT-04P, SenseGuard DW Gen3 |
| Radio | Matter over Thread or Zigbee 3.0; one mode at a time |
| Power | Two replaceable LR03 AAA batteries |
| Sensor size | 90 × 26 × 13.5 mm |
| Magnet size | 31 × 14 × 6.5 mm |
| Weight | 45.1 g with batteries |
| Installation gap | Up to 30 mm horizontally or 15 mm vertically |
SONOFF claims up to 15 months of battery life and a 100-metre communication distance in an open area. Neither figure is a guarantee for an installed home: walls, radio congestion, mesh placement, reporting frequency and battery quality will affect the result.
What Home Assistant users get
In Thread mode, the sensor commissions as a Matter accessory. Home Assistant appears in SONOFF’s supported-platform list, but a working Matter controller and Thread Border Router are still required. Our Matter-over-Thread and Home Assistant guide explains those separate roles and the local IPv6 path between them.
Thread mode exposes open/closed state and battery level to Home Assistant according to SONOFF’s compatibility table. It does not expose the tamper state to any listed Matter platform. That is the largest functional difference hidden behind the dual-radio headline.
Zigbee mode needs a compatible coordinator or gateway. SONOFF lists its own bridges and USB dongles, plus ZHA and Zigbee2MQTT for Home Assistant. The current support page says ZHA still needs a SONOFF-supplied script, so buyers should not assume completely automatic stock-ZHA discovery. In this mode the Home Assistant column lists open/closed, battery and tamper status.
The radio choice can be changed later, but switching modes resets the device and requires fresh pairing. It cannot stay in both a Matter fabric and a Zigbee network. This is similar to the architectural choice discussed in our ESPHome 2026.11 Thread and Zigbee coverage: sharing 802.15.4 hardware does not automatically make two protocol stacks available at once.
Firmware and installation caveats
- Zigbee OTA has a version gate. SONOFF says firmware below 1.0.7 cannot receive Zigbee OTA updates. Those units must first use the eWeLink app’s Bluetooth Quick OTA process.
- The magnet alignment matters. The 30 mm allowance applies to horizontal mounting; vertical mounting is limited to 15 mm.
- Thread is not Wi-Fi. The sensor needs a compatible Thread Border Router and cannot join a normal wireless LAN directly.
- Tamper behaviour depends on the route. Zigbee support varies by gateway, while SONOFF’s own matrix marks tamper as unavailable throughout Thread mode.
Makers who prefer a fully custom device can instead build an ESP32 reed-switch door sensor with ESPHome, trading the finished enclosure and replaceable-battery design for control over firmware and exposed entities.
Price and availability
SONOFF’s store currently accepts orders at £20.88 including tax in the UK and US$22.90 before tax in the United States, with shipping calculated at checkout. Regional price and stock can differ. The product reached SONOFF’s direct store on 10 November; separate retailer pre-orders and delivery dates should not be treated as confirmation of stock in every market.
