The Extech 45170 is a rugged, pocket-sized 4-in-1 environmental meter that combines humidity, temperature, air velocity, and light measurement in one convenient instrument. Its ergonomic design fits comfortably in your hand or pocket, making it ideal for HVAC technicians, facility managers, and indoor air quality professionals who need quick, reliable readings on the go.

The large dual LCD simultaneously displays temperature alongside air velocity or relative humidity for easy monitoring. Air velocity is measured from 80 to 5910 ft/min using a low friction vane wheel, with selectable units including ft/min, MPH, m/s, km/h, and knots. A precision thin‑film capacitance humidity sensor provides fast response from 10 to 95% RH, while a built‑in thermistor measures ambient temperature from 32 to 122°F. For high‑temperature applications, the meter accepts an optional Type K thermocouple (not included) to measure up to 2372°F. Light measurements are cosine and color corrected, covering 0 to 20,000 lux.

Field‑friendly features include Data Hold to freeze the display, Min/Max recording for trend analysis, and an auto power off function (disableable) that activates after 10 minutes of non‑use to conserve battery life. Low battery and overrange indications ensure reliable operation.

The Extech 45170 ships complete with built‑in sensors, wrist strap, and 9V battery—ready for immediate use. Typical applications include HVAC system checks, indoor air quality assessments, facility maintenance inspections, and lighting surveys.

Features

• 4-in-1 measurement: air velocity, humidity, temperature, light
• Air velocity range: 80 to 5910 ft/min (±3% accuracy)
• Humidity range: 10 to 95% RH (fast response capacitive sensor)
• Temperature: built-in thermistor (32 to 122°F) plus Type K input (up to 2372°F)
• Light range: 0 to 20,000 lux (cosine and color corrected)
• Large dual LCD for simultaneous readings
• Data Hold, Min/Max recording
• Auto power off (disableable), low battery/overrange indication
• Ergonomic pocket-sized housing
• Includes wrist strap and 9V battery