First of all, selenium is a trace element. A better cup costs tens of dollars, and a dozen cups can supplement selenium. This must be false. In this case, how can you make those selenium supplements sell for one or two hundred dollars? Personally, I think there is only one way to supplement selenium in a selenium-enriched cup, that is, take the water sample in the cup to a testing institution for testing to see if it really contains selenium. A cup has the function of supplementing selenium, which is definitely different from a normal cup.