Extech Instruments Pinless Moisture Meter-MO257 - The Home Depot

Extech Instruments

Model # MO257

Internet # 203449697

Pinless Moisture Meter

Extech Instruments Pinless Moisture Meter

This item has been discontinued.
The Home Depot no longer carries this specific product.

$209.99 / each


Model # MO257

Internet # 203449697

Pinless Moisture Meter for non-invasive measurement in wood and other building materials with virtually no surface damage. Measurement depth from 078 in. (20mm) to 1.6 in. (40mm) below the surface. Two user-settable alarm levels with audible beeper and visual flashing RISK or WET indicators. Triple backlit LCD. Complete with 3 AA batteries and pouch case.

  • Non-invasive moisture content measurements in wood or building materials
  • Relative pinless moisture reading for non-invasive measurement from 0.0 to 100.0 with 0.1 resolution
  • Multifunction backlit triple LCD display
  • Pinless measurement depth from 0.78 in. (20mm) to 1.6 in. (40mm) below the surface
  • High frequency sensing technology

Info & Guides

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Assembled Depth (in.)  5.3 in  Assembled Height (in.)  12.8 in 
Assembled Width (in.)  1.6 in  Product Depth (in.)  2.5 
Product Height (in.)  9.25  Product Width (in.)  1.1 
Abrasion-Proof Display Lens  No  Audible Alert  Yes 
Automatic Calibration  Yes  Automatic Temperature Compensation  No 
Case Included  Yes  Control Type  Digital 
Data Log/Record  No  Data hold  Yes 
Display Type  Digital  External Electrode  Not Supported 
Extra Pins/Probes Included  No  Hazardous Code  null 
Interchangeable Pins/Probes  No  Maximum moisture reading (%)  100.0 
Maximum sense depth (in.)  1.6  Measureable materials  Wood and Building Materials 
Microcontroller Circuit  Yes  Minimum moisture reading (%)  0.1 
Product Weight (lb.)  0.5 lb  Reference Scale Included  No 
Returnable  90-Day  Solar  No 
Test Meter Type  Moisture Meter  Tools Product Type  Test Meter 
Warranty / Certifications
Manufacturer Warranty  1 Year 


Rated 4.8 out of 5 by 19 reviewers.
Rated 5.0 out of 5.0 by How dry it is... This meter is designed to quickly sweep large areas looking for excess moisture in drywall and wood. It gives a relative readout between 0 (dry) and 100 (wet), but is not calibrated for exact percentages. A table in the manual gives some general guidance - drywall is dry below 30, wood is dry below 50, and cement is dry below 25. You have to calibrate it before every use, which takes about 6 seconds. It does detect moisture in humans, so you will need to recalibrate if you change your hand position on the meter. The other controls are easy to use. You'll probably only set the alarm ranges once, but you'll want to keep the manual handy. There's a two-step process to turn it on - first press the power button, and then it won't do anything until the "MEAS" button is pressed to start the calibration process, after which measurements can be taken. Pressing MEAS again will freeze (HOLD) the reading - a convenience when measuring in spots where you can't read the display. For some reason the meter automatically turns off in 30 seconds after taking a HOLD reading unless you press MEAS again to release the hold. The normal auto-off period is a generous 30 minutes. In my 26-year-old house, I swept around all windows, doors, and skylights, as well as all the plumbing fixtures. I not find any leaks. I plan to recheck every six months. While scanning my house, I discovered that it thinks metal is wet - curtain rods and drywall metal corner bead would send the meter over 40 and trigger the "risk" alarm. I checked my dry firewood and it measured between 20 and 30. Really dry wood (indoor furniture) measured between 5 and 15. Dry lumber measured between 15 and 20, so I'll assume that anything under 20 is suitable for woodworking or construction. I have a cement basement floor and it measured between 50 and 60, well over what the manual considers wet. One weird thing - a mini-CD was included that said it contained product manuals, but a printed User's Guide was included and the mini-CD was an unwritten CD-R. November 2, 2014
Rated 4.0 out of 5.0 by Great Meter easy to use takes the guessing out of wondering if a wall is damp Great Meter easy to use takes the guessing out of wondering if a wall is damp. This is a handy tool to keep if you want to know if a stain wall is still damp or old stains . Makes the trouble shooting very easy to determine what course of action you should take to make repairs. Nice case to keep meter safe . November 5, 2014
Rated 5.0 out of 5.0 by excellent professional meter This meter is just what my husband needed to check our basement for moisture in various areas. The product calibrates easily and the readings are clearly displayed. The product has a LCD screen. This is a professional product and has high functioning technology. The meter came with batteries and a very nice carry pouch that will protect it when not in use. My husband was very pleased with this product, which allows him to check the areas, without tearing out the walls. December 16, 2014
Rated 4.0 out of 5.0 by Well built and easy to use After a little trial and error I can feel confident this works as advertised. A friend who is an electrical engineer tested this alongside his pin meter to explain the way it works and why some readings were not what I expected. I knocked one star off because the instructions should include examples of what to expect and how different textures or wood types will affect the readings. For example if the probe touches two edges of a wall it will almost double the reading. Also if it is near or touches metal it will not be accurate. On the bright side it could double as a stud finder if you hit a nail or screw in the wall the reading will spike. Probably a no brainer for experts but the average DIY would appreciate it. I got this as an all around tool for measuring moisture behind various surfaces in the house. Turns out this is a great meter for these uses. it is very easy to use and has nice features so if you are a home owner and can afford this one it is a good choice. Definitely do some research before buying so you know how to use this and which type of meter works best for your uses. Youtube has plenty of videos with examples. November 5, 2014
Rated 5.0 out of 5.0 by Very Handy for Large Jobs This is a great meter for water & mold remediation jobs. Unlike a typical moisture meter, this unit runs a scale from 1 (DRY) to 100 (DRIPPING WET) There is a scale in the users manual that will give you a conversion to percentages. It also measures to almost 2 inches deep. I've been using this on large water jobs from a leaky roof to burst water pipes. I sweep large areas and mark them off with a marker so the crew can come in and remove the offending drywall and insulation right away and position fans where they need to be. You can also use this during and after cleanup to make sure your in the safe zone.. Its a good sturdy meter at what I thought was a reasonable price, December 31, 2014
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