• Air velocity range: 0 to 4000 fpm
  • Temperature range: -4 to 160°F
  • Flow, volume flow (cfm) and temperature measurements
  • Multi-point and timed mean calculations
  • Max-Min values make comparisons fast and easy
  • "Hold" button freezes readings
  • Clear backlit display
  • TopSafe provides water, dirt and impact protection


The Testo 425 thermal anemometer is a compact, easy to use anemometer with attached thermal probe on a telescopic handle. The Testo 425 thermal anemometer measures air velocity from 0 to 4000 fpm and temperatures from -4 to 160°F. Volume flow can also be measured by simply entering the duct measurements into the Testo 425 thermal anemometer.

The Testo 425 thermal anemometer displays reading on a large, clear display. Switching between flow and temperature readings is easy. The Testo 425 thermal anemometer includes timed and multi-point mean flow calculations which allow for easy flow analysis, volume accumulation estimates, and temperature variation monitoring. Min-Max values are one button simple, while the "Hold" function freezes the current readings in the display for easy data recording.

The Testo 425 thermal anemometer ships complete with meter, probe, telescopic handle (max. 33 inches), battery, and calibration document.