Light weight, tiny size with simple, one-hand, operation. Will sense airflow as low as 0.4 m/s with an accuracy of ±3% (4% >20m/s). Replaceable snap-in anemometer vane. All models feature min/max, hold, a backlight and come complete with a wrist strap, carry pouch, and button cell battery providing at least 40 hours of continuous use.