Answer:
R-factor.
Step-by-step explanation:
Insulation can be defined as the process in which physical objects (materials) oppose the flow of current by providing a least resistance path or the opposition to the conduction of heat energy.
R-factor is an abbreviation for thermal resistance. The R-factor is the most commonly used measurement for providing all of the informations about the insulating properties of an insulator. Therefore, the measurement used for insulation is called the R-factor.
Most manufacturers specify the R-factor on the label of an insulating material.
Generally, the higher the R-factor of an insulating material the better it is for insulation.
Hence, the ability of a material to prevent the flow of heat or electricity (current) is largely dependent on its R-factor.