The ELECROW Crowtail HTU21D Humidity & Temperature Sensor 2.0 is a compact, fully digital environmental monitoring module built around the HTU21D sensor. It provides highly accurate measurements of relative humidity and temperature, with digital output over the I²C bus, which simplifies integration with microcontrollers like Arduino, ESP32, and others. Designed for low-power applications, it is ideal for use in weather stations, data loggers, HVAC monitoring, indoor environmental control, or humidor systems. The wide operating temperature range and full RH span make it versatile for both cold and warm conditions. The module has fast response speed, good stability over time (low drift), and low hysteresis, meaning it retains accuracy over repeated cycles and varying humidity. It comes in Crowtail form factor, using the standard Crowtail cable for easy plug‑in to Crowtail shields or base modules. While the module can accept a supply of 5V, its internal sensor runs at lower voltage (1.5‑3.6V), so proper consideration for voltage regulation is needed in some setups. Overall, it delivers precision, stability, and reliability in a small package.