This flat bottom tumbler is from my personal collection which I have had over 40 years.  I was very selective when purchasing and didn’t buy any with flaws.   It is both still bright and shiny with good yellow color.  It measures 5 1/8 inches tall and 3 1/4 inches diameter.  It is often referred to as the Iced Tea glass.  I am starting to break up my set and will be listing other pieces if interested.  Questions welcome.