One of the parameters that is of paramount importance for almost any object, device or material is temperature. It can change physical properties and parameters of materials or can indicate a malfunction in a device. But when using a thermometer or data logger is difficult or impossible special additional substances and gadgets are used to monitor temperature levels. An example can be a temperature label or a temperature plate. It is essentially a heat monitor that is made of a temperature-sensitive indicator, which is sealed under a see-through covering that protects the sensitive part from the heat. Such devices are attached to the surface of an object we desire to monitor, and they indicate the temperature of a material they’re covering. Some labels and strips may be reversible, they act like a normal thermometer, indicating current temperature. Irreversible appliances are not reusable, if the maximum temperature was achieved and indicating parts were used they will not revert to their original state. Another example is a temperature stick, a specialized crayon that contains heat-sensitive parts, which change color when their triggering temperature is achieved.