From: General Tools
Moisture Meters from General Tools measure the absolute or relative moisture content of wood or a building material such as drywall. They also can be used to further determine if a surface is dry enough to be painted or joined. Moisture Meters easily detect hidden leaks in wood, plastic and carpet, and they are great for locating roof leaks, discovering the extent of water damage, and selecting dry lumber. The three latest models are the MM7, MM8 and MM9.