Functional model. "Functional drink" (red bull vitamin functional drink) is usually considered as the most authentic red bull product. This is because it is the earliest red bull drink, and because it contains a higher proportion of caffeine, it is more effective. In addition, other brands such as Flavor (Red Bull Vitamin Flavor Beverage), Anergi (Red Bull Anergi Beverage) and Taurine (Red Bull Vitamin Taurine Beverage) are also legal brands authorized by Thai Tencel, so they also belong to the category of authentic Red Bull products. As for Austrian Red Bull and Thai Red Bull, although they are produced by different companies in different countries, they are also officially authorized by Thai Tencel, so they are considered genuine.