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The Extech 445715 Big Digit Remote Probe Hygro-Thermometer is a compact environmental monitor that displays temperature and relative humidity simultaneously on a large dual-line LCD. The integrated sensor probe can clip directly onto the meter housing for stationary bench or wall-mounted monitoring, or extend on its 18-inch (457 mm) cable to place the sensing element in a location separated from the display — useful when the area being monitored is not the same as the area where the reading is observed.
A hygro-thermometer of this type is used to track ambient temperature and relative humidity in environments where those parameters matter to a process, a product, or occupant comfort. The 445715 covers a measurement range of 10 to 99% RH and 14 to 140°F (-10 to 60°C), which encompasses typical indoor environments along with warmer and cooler controlled spaces. The Max/Min recording function with reset captures the highest and lowest readings observed between resets, so a user returning to the meter after an interval can see the extremes that occurred rather than only the instantaneous value.
Extech Instruments was founded in 1971 and was acquired by FLIR Systems in 2007, operating as an FLIR company. FLIR Systems itself was subsequently acquired by Teledyne Technologies in 2021, bringing the Extech product line into the Teledyne FLIR portfolio. The Extech brand identity has been maintained across both transitions for its established position in handheld environmental and electrical test instruments.
The 445715 is offered in two ordering configurations sharing the same hardware platform and specifications. The base 445715 ships as the standard instrument; the 445715-NIST variant adds a calibration certificate traceable to NIST for users whose quality system or documentation requirements call for NIST-traceable measurement equipment.
The optional RH300-CAL accessory — a set of 33% and 75% RH calibration salt-bottle standards — is a separate item that supports periodic field calibration of either base unit. Customers selecting between the two ordering codes are choosing on the basis of calibration documentation needs, not on instrument performance, since the measurement hardware is identical.
Each new model below is its own dedicated product page with condition-matched pricing. Configurations differ in calibration documentation, not in measurement specifications, so the right choice depends on whether NIST-traceable documentation is required at the time of purchase.
The two ordering codes share the 10 to 99% RH humidity range, the 14 to 140°F temperature range, the ±4% RH and ±1°C/1.8°F accuracy specifications, the 18-inch (457 mm) probe cable, the Max/Min function, the rear calibration adjustment pot, and the included sensor, mounting bracket, and AAA battery. The hardware is the same; the differentiator is documentation.
The 445715-NIST adds a calibration certificate with measurements traceable to NIST, which is the relevant choice for users operating under a quality system that specifies traceable calibration for environmental monitoring equipment. The base 445715 is appropriate where calibration documentation is not a requirement of the application. The RH300-CAL salt-bottle calibration kit is an independent accessory that can be added to either ordering code.
| Model | Humidity Range | Temperature Range | Accuracy |
|---|---|---|---|
| 445715-NIST | 10 to 99% RH | 14 to 140°F (-10 to 60°C) | ±4%RH; ±1°C/1.8°F |
| 445715 | 10 to 99% RH | 14 to 140°F (-10 to 60°C) | ±4%RH; ±1°C/1.8°F |
Additional differences in specifications beyond the few shown above are not listed here — see each model's full specifications below.
| Specification | Value |
|---|---|
| Humidity Range | 10 to 99% RH |
| Temperature Range | 14 to 140°F (-10 to 60°C) |
| Accuracy | ±4%RH; ±1°C/1.8°F |
| Functions | Max/Min with reset function |
| Calibration | Rear calibration adjustment pot |
| Probe | Clips onto meter or extends on 18 in. (457 mm) cable |
| Dimensions | 4.3 x 3.9 x 0.78 in. (109 x 99 x 20 mm) |
| Weight | 6 oz (169 g) |
| Power | 1 AAA battery (included) |
| Included Accessories | Built-in stand, mounting bracket, sensor, and 1 AAA battery |
| Optional Accessory | RH300-CAL 33% and 75% RH calibration salt bottles |
Please review the Manufacturer's Data Sheet to verify published specifications. Feedback on this webpage is always welcome — please reach out to your Test Architect at any time for questions or concerns. Thank you, we truly appreciate you being our customer.
Model No
Extech
Condition
New
Manufacturer
Extech
30+ Years in Business
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30+ Years in Business
Secure Payments
Sell Test Equipments
Knowledgeable Staff
On-site Lab
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