The material moisture of wood and materials such as cement, concrete and plaster can be measured quickly and accurately using material moisture meters. This means that builders and tradesmen can continue their work without delay, if the material moisture or dryness has reached a specific level or is below it. In this way it is possible to eliminate waiting times that are too long or short and cause extra costs. These devices can also be used to check if walls, in a cellar for example, are too moist, possibly causing the growth and spread of mould. If this is the case, it is possible to act quickly and take measures. Thermo-hygrometers in pen form are particularly robust and handy. They are used particularly in the areas of heating, climate and sanitary. Material moisture is checked by a simple brief contact.