Our King of Pu'Er is the second highest grade, having been fermented underground for an incredible 8 years. The highest grade is 10 years, the lowest just 6 months. Think vintage wine of the tea world! The fermentation process means it is a source of probiotics which some people find helps improve digestion as well as many other possible benefits reported. Due to the time spent underground, it has an earthy taste which our customers have come to love.