General Tools MMH800 Pin/Pinless Moisture Meter with Temperature and Humidity

General Tools MMH800 Overview

The General Tools MMH800 is a multifunction moisture meter that combines direct pin measurements, non-invasive surface scanning, ambient temperature and relative-humidity measurement in a single handheld instrument. That combination makes it particularly useful for restoration, leak detection and general building inspection where both the material and the surrounding air conditions matter.

Instead of carrying separate tools for basic material moisture and room humidity, the MMH800 provides two dedicated displays: one for moisture and another for ambient temperature and RH.

Pin and Pinless Moisture Detection

The meter includes sharp contact pins for direct measurement as well as a non-invasive inductive sensor. Pin mode is useful when the user needs a reading from a precise location and small puncture marks are acceptable, while the pinless function helps locate moisture without repeatedly piercing the surface.

General Tools specifies a 5–50% WME range for wood and a 1.5–33% range for building materials in its moisture measurement system. Pin-mode accuracy is specified at ±3% with 0.1% resolution.

Useful for Floors, Subfloors and Building Materials

The MMH800 is intended for materials including lumber, unfinished wood, drywall, plastered walls, carpeting, floors, subfloors, brick and grout. This broad range makes it useful when investigating a building where moisture may move through several different materials.

For flooring work, the meter can help compare wood and subfloor conditions before or during a moisture investigation. For restoration, it can be used around damaged drywall, masonry and other surfaces to identify areas that still show elevated moisture.

Ambient Temperature and Relative Humidity

A major advantage over simpler moisture meters is the integrated environmental measurement. The MMH800 measures ambient temperature from 32°F to 140°F and relative humidity from 25% to 95%.

This is useful during drying work because material moisture does not exist in isolation. Tracking room temperature and RH alongside surface readings gives the user more context when evaluating whether conditions are suitable for drying, finishing or further inspection.

Visual and Audible Moisture Alerts

The meter provides audible and visual high, medium and low moisture indications. This allows users to scan an area quickly without concentrating on the exact number for every single test point.

A data-hold function freezes the current reading for easier viewing, while the pin cover doubles as a calibration checker. Automatic diagnostic checks, battery indication and auto power-off help simplify routine field use.

A Practical Tool for Water-Damage Investigation

In restoration work, the MMH800 can be used to compare material readings while also checking the surrounding humidity. This makes it useful around leaks, damaged drywall, damp wood, subfloors and other areas where both moisture content and drying conditions need attention.

The pinless sensor is intended for surface-level non-invasive detection rather than the deeper scanning offered by some specialist meters, so users looking for deep pinless measurements should consider that limitation.

Who Is the MMH800 Best For?

The MMH800 is a strong general-purpose choice for users who want several basic moisture and environmental functions in one tool. It is well suited to home inspectors, restoration professionals, woodworkers and flooring users who need flexibility more than highly specialized measurement.

For advanced reporting, deep scanning or dedicated concrete-floor testing, a specialist instrument may be more appropriate. For mixed everyday moisture checks, the combination of pin, pinless, temperature and humidity functions gives the MMH800 broad practical value.