SONOFF SenseGuard DW Gen2
SONOFF SenseGuard DW Gen2
SONOFF SenseGuard DW Gen2 (SNZB-04PR2) is a completely redesigned Zigbee 3.0 door and window sensor, built to solve the biggest complaints smart home enthusiasts have with standard contact sensors. Sonoff has moved away from hard-to-find coin cell batteries and unreliable mechanical "reed" switches of older models, opting instead for standard AAA batteries, a solid-state Hall effect sensor, and built-in physical tamper detection.
With an ultra-slim 13.5 mm profile, this sensor blends seamlessly with modern window and door frames, while providing instant, local feedback to your smart home server.
Key features
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Upgrade to AAA batteries: Say goodbye to expensive, less common CR series coin cells. The Gen2 runs on two standard, easily accessible AAA batteries, providing up to 3 years of continuous operation.
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Solid-state Hall effect sensor: Instead of a traditional mechanical reed switch (which can suffer from contact bounce or wear out over time), this sensor uses a solid-state Hall effect chip for electronic magnetic field detection. This results in faster and completely reliable open/closed reporting.
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Active tamper detection: Security is built-in. On the back of the sensor is a physical tamper button that is pressed against your door frame. If an intruder tries to tear the sensor off the wall or window, the button is released and immediately triggers a tamper alert in Home Assistant or the eWeLink app.
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Ultra-slim design: With a thickness of only 13.5 mm, it is significantly thinner than previous generations, allowing it to fit flat and unobtrusively on almost any door frame, cabinet, or window without catching on sliding tracks.
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Flexible magnet installation: The new sensor supports both horizontal and vertical magnet alignment, giving you greater flexibility for doors or frames with unusual trim or narrow gaps. (Provides up to 30 mm of detection range horizontally and 15 mm vertically).
Technical specifications
| Feature | Specification |
| Model | SNZB-04PR2 (SenseGuard Series) |
| Detection technology | Solid-state Hall effect sensor |
| Wireless protocol | Zigbee 3.0 (IEEE 802.15.4) |
| Power supply | 2x AAA battery (LR03) 1.5V (included) |
| Battery life | Up to 3 years |
| Detection distance | 30 mm (horizontal alignment) / 15 mm (vertical alignment) |
| Platform compatibility | Home Assistant (ZHA and Zigbee2MQTT), eWeLink, Alexa, Google Home |
| Operating temperature | -10 °C to +60 °C |
| Housing material | Flame-retardant PC (polycarbonate) |
| Dimensions (transmitter) | 90 mm × 26 mm × 13.5 mm |
| Dimensions (magnet) | 31 mm × 14 mm × 6.5 mm |
| Weight | 45 g (including batteries) |
Package contents
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SONOFF SenseGuard DW Gen2 (SNZB-04PR2) transmitter
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Magnetic contact unit
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2x AAA battery (pre-installed)
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3M double-sided adhesive pads for mounting
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Quick start guide