The General Tools MMH800 4-In-One Pin/Pad Rh Moisture Meter is designed for use in woodworking, water damage restoration, building construction and home renovation.

Because it can measure ambient temperature and humidity in addition to moisture level, the General Tools MMH800 4-In-One Pin/Pad Rh Moisture Meter is particularly suitable for water damage restoration projects.

The meter has two LCDs: one displays moisture level and the other - a split-screen display - monitors temperature and humidity. A dedicated front-panel button selects the default temperature unit (degrees Fahrenheit or degrees Celsius).

The 4-in-1 part of the meter's name refers to its ability to measure: 1) temperature; 2) relative humidity; 3) moisture level using a pin sensor; and 4) moisture level using a pad sensor. The meter has both kinds of sensors, with a pair of pins on top and a split metal pad on the back. Both sensors base their measurements on the relationship between the moisture content of a material and its electrical conductivity. The wetter a material, the higher its conductivity.

In both cases, the sensors serve as the electrodes of a conductivity meter optimized for measuring moisture content.