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Internet #205078069

Model #RHMG650

Store SKU #1000508784

9-in-1 Thermo-Hygrometer Pin/Pinless Moisture Meter with Probe and Carry Case

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  • 9 different measurements (humidity, dew point, vapor pressure)
  • Range -20 to 167°F recalls 20 reading pairs, large backlit LCD
  • Uses: water damage repair, facility maintenance & HVAC/R installs
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Product Overview

Since 1910, General Tools has grown to become a recognized industry leader for specialty hand tools and instruments. The General Tools Multi-Function Thermo-Hygrometer with Pin/Pinless Moisture Meter can measure 1) ambient temperature, 2) relative humidity (RH), 3) absolute humidity (in mg/L or g/m3), 4) GPP (mixing ratio in grains per pound or g/kg), 5) relative moisture level using pinless sensor, 6) absolute moisture level using included pin-type probe, 7) dew point, 8) atmospheric pressure and 9) vapor pressure. It's ideal for water damage restoration contractors, facility maintenance professionals and HVAC system installers/technicians.
  • Stores/recalls 20 pairs of readings
  • Settable high and low alarms for RH, relative moisture level and absolute moisture level
  • Backlit LCD with 3-digit primary readout plus 4-digit secondary readout
  • Field calibratable humidity measurement
  • Min/max, data hold and 30-minute auto power off functions
  • Ambient temperature measurement range/accuracy: -20 to 167˚F
  • RH measurement range: 0 to 100%
  • RH measurement accuracy: ±2.5% from 11 to 90%RH; ±3%RH elsewhere
  • Absolute humidity range: 0.5 to 240mg/m3
  • GPP range: 0 to 999/GPP (0 to 160g/kg)
  • Relative/absolute moisture level range: 0 to 99.9%
  • External moisture probe measurement accuracy/resolution: ±3%/0.1%
  • External probe pin length: 3/8 in. (10 mm)
  • Dew point range: -76 to 140˚F
  • Atmospheric pressure range: 30 to 120 KPA
  • Includes meter, external moisture probe and soft carry case
  • California residents



Product Depth (in.)1.4Product Height (in.)7.3
Product Width (in.)2.8


Battery Power TypeAlkalineBattery Size9-volt
Control TypeManual/AnalogDisplay TypeDigital
Electrical Tools FeaturesAbrasion-Proof Display Lens,Automatic Calibration,Automatic Temperature Compensation,Backlit,Data Hold,Data Log/Record,Interchangeable Pins/ProbesExternal ElectrodeIncluded
Maximum Moisture Reading (%)99Maximum Sense Depth (in.).75
Measureable MaterialsVariousMeasures/DetectsHumidity
Minimum moisture reading (%)0Number of Batteries Required1
Product Weight (lb.).39Returnable90-Day
Test Meter TypeMoisture MeterTools Product TypeTest Meter

Warranty / Certifications

Manufacturer Warranty1 Year

Questions & Answers

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Customer Reviews

  • 3.8
    out of 8 reviews
  • 100%recommend this product
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Showing 1-8 of 8 reviews
Product was delivered used / clearly second hand, not new....
Product was delivered used / clearly second hand, not new. Am returning to store for refund at first opportunity.
    Very satisfied with the performance however it’s difficult to read...
    Very satisfied with the performance however it’s difficult to read the screen you have to look at it at a 45° angle. Planning on taking it back to have it replaced. Would buy again
    • Verified Purchase
    This is a less expensive version of the meter I...
    This is a less expensive version of the meter I had originally wanted. That said this meter performed very well. I am an RV Inspector so the non-invasive meter was essential. It works well on all interior surfaces of the unit and allows me to give my customers a better indication of condition.
    • Verified Purchase
    Good all around water meter ...
    Good all around water meter
    • Verified Purchase
    This thing is a great tool, we kept having window...
    This thing is a great tool, we kept having window sills and other trim crack and peel every year and really think the wood wasnt dry enough. Now we dont take any chances and check everything. Its a hot gizmo!
    • Verified Purchase
    Meter works just as well as more expensive obes...
    Meter works just as well as more expensive obes
    • Verified Purchase
    2 found this review helpful
    4 star
    Great meter for the price. Has everything a $500 flir or extech meter would have. I bought 5 of these for my techs reason for 4 stars was because on 2 of the sets the prongs on the attachment were not pointed but instead hooked at the ends and when the first time i used it of course had to be on looped pile carpet and it hooks and pulls the loops coming back out of the carpet. Will have to file the tips down but shouldnt have to do so. Otherwise great product.
      • Recommended
      2 found this review helpful
      General Tools & Instruments RHMG650
      Super unit! Inexpensive and reliable. Readings are dead on! Used multiple readers on one job site this little unit was more accurate than the rest! Going to purchase another 12 for the rest of my techs. Recommended by a field adjuster and a home inspector. For the price why not?
      • Recommended
      4 found this review helpful
      Showing 1-8 of 8 reviews