# R—Reflectivity > [!note] 이 페이지는 아직 한국어로 번역되지 않아 영어로 표시됩니다. 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.