Frequently Asked Questions
Everything you need to know about purchasing, warranty and our devices.
Everything you need to know about purchasing, warranty and our devices.
€12.00
SONOFF AirGuard TH Lite (SNZB-02B) is an extremely compact and highly accurate Zigbee 3.0 temperature and humidity sensor that brings professional environmental monitoring in a small format. While basic sensors only report temperature and humidity, the AirGuard TH Lite goes a step further by calculating Dew Point and Vapor Pressure Deficit (VPD) — critical metrics for preventing mold, protecting sensitive electronics, or optimizing indoor greenhouses.
Since it uses standard AAA batteries instead of expensive button cells, it is easier to maintain and provides up to 2 years of reliable operation.
Key Features
High-precision sensing: Powered by a premium Sensirion sensor and providing exceptional accuracy (±0.2 °C and ±2 % RH), you can fully trust the data that drives your climate automations.
Advanced environmental metrics: In addition to standard temperature and humidity, it intelligently calculates dew point (to warn you about condensation) and VPD (essential for plant care and greenhouse monitoring).
5-second refresh rate: Unlike older sensors that only update every few minutes, the AirGuard TH Lite can report changes as often as every 5 seconds, ensuring that your smart fans, heaters, or dehumidifiers react instantly to sudden climate changes.
Standard AAA batteries: Instead of less common CR-series button cells, this sensor operates on two standard, widely available AAA batteries, ensuring up to 2 years of continuous operation, depending on the reporting frequency.
Universal Zigbee 3.0 compatibility: It integrates seamlessly into local smart home platforms such as Home Assistant (via ZHA or Zigbee2MQTT), SmartThings, and eWeLink, requiring a compatible Zigbee coordinator.
Technical Specifications
| Feature | Specification |
| Model | SNZB-02B (AirGuard TH Lite) |
| Wireless protocol | Zigbee 3.0 (IEEE 802.15.4) |
| Measured values | Temperature, relative humidity |
| Calculated values | Dew point, vapor pressure deficit (VPD) |
| Temperature accuracy | ±0.2 °C |
| Humidity accuracy | ±2 % RH |
| Data refresh rate | Up to every 5 seconds |
| Power supply | 2x AAA battery (LR03) 1.5V (included) |
| Estimated battery life | Up to 2 years |
| Platform compatibility | Home Assistant (ZHA, Zigbee2MQTT), eWeLink, SmartThings, Amazon Alexa (with Zigbee hub) |
| Operating temperature | -20 °C to +60 °C |
| Operating humidity | 5 % to 95 % RH (non-condensing) |
| Dimensions | 66.3 mm × 27.8 mm × 20 mm |
| Weight | ~43 g (including batteries) |
| Housing material | White polycarbonate (PC) |
Package contents
SONOFF AirGuard TH Lite sensor (SNZB-02B)
2x AAA battery (pre-installed)
Adhesive mounting pad and lanyard for hanging
Quick start guide
If you'd like to know anything before buying – delivery, availability, technical specifications or the actual condition of the device – we're happy to help. Contact us also if you need larger quantities or are looking for a smart home device that isn't in our catalog.
Message us and we'll gladly help you!