Gives moisture reading based on electrical resistance across 2 pins LCD screen with dual measurement bar graph Measures moisture in wood from 6-44 Percent Measures masonry (mortar, concrete, plaster) moisture from 0.2 - 2.0 Percent Two detection pins (8mm length) to locate in material being tested Verifying Unit Calibration: There are 2 pairs of metal test sockets on the top of the cap, these can be used to test the moisture meter Touch the 2 probes to the metal contacts marked "T", the reading on the wood scale should be 19% ±1. Now touch the new probes to the 2 metal contacts marked "B", a indication bars should blink on the LCD display. If the moisture meter operates as mentioned above, the unit is working properly.