# R—Reflectivity > [!note] Esta página ainda não foi traduzida e é apresentada em inglês. The Mean Reflectivity index R represents the average reflectivity value of the surface, or a value for how the surface interacts with light, contributing to its visual characteristics such as gloss and brightness. Reflectivity is an absolute measurement but uses a non-standard unit (arbitrary units [arb'U]) specific to the measurement system.